Overview of AP Human Geography Unit 2

So your AP HUG Unit 2 exam is coming up and you are so lost and confused that your soul feels like I feel when I open a 2-pack of Starburst and they are both LIMITED. But hey, what if I told you that Unit 2 is definitely understandable if you just had someone to splain it up real nice for you, and by the end of this video you'll have everything you need to crush that exam? Well, it's true, and that someone is me, Steve Heimler. So if you're ready to get them brain cows milked. Let's get to it. Now let's begin in the beginning and talk about population distribution. So when we talk about population, we're talking about groups of people. Population distribution refers to the pattern of human habitation on the Earth's surface. If every single person were spread out evenly over the Earth's surface, each of them would have about two football fields on which they could live. And, you know, that'd be nice, but the Earth's humans are not, in fact, evenly distributed. Some people live isolated and miles from other humans, while others live packed together tighter than canned yams, which, you know, can be pretty tight. Anyway, we need to understand. why the differences in population distribution exist, and there are two basic factors. But before I tell you what those are, let me remind you that if you want to get an A in your class and a 5 on your exam in May, then click the link below and have a look at my AP Human Geography Heimler Review Guide. This thing has exclusive unit review videos that are not here on YouTube. They have note guides to follow along with those videos, practice questions, a full practice exam, a free demo of my AI Heimler Bot which is going to help you answer any question you have and score your responses. It is the fastest and most comprehensive way to study for this course, so check it out. And now back to the video. Back to the two factors that explain population distribution. First are physical factors. You see, because humans depend on the environment for their survival, the various features of the earth often determine where people live. So one physical factor that affects population density is climate. People tend not to live in high numbers where the climate is harsh. You know, if it's too wet or butt cold or too dry or whatever, less humans tend to live in those places. For example, most of the population in Australia is distributed near the coast. coast where the temperatures are more temperate and almost nobody lives in the center where it's dry and hot enough to fry eggs in the dirt. So for the most part, humans love to live in the mid-latitudes, between 30 and 60 degrees from the equator because the temperature is milder and there's a decent amount of precipitation. Okay, now a second physical factor in population distribution is landforms. In general, humans like to live in lowland areas because in those areas it's easier to build and easier to farm. Mountainous areas, on the other hand, tend to be sparsely populated. Hey, can I borrow some sugar? And that's not hard to understand. Higher elevations bring... bring challenges to human life like nasty cold temperatures, minimal food, and lack of breathable air. But this is only true in the middle and higher latitudes. In places close to the equator, some mountainous regions can be highly populated precisely because they're cooler and more temperate. Okay, now a third physical factor that affects population distribution is water. From the dawn of human history, human settlements have gathered around bodies of water, either rivers or oceans or lakes. Again, not hard to understand. These bodies of water provide people with what they need to live, like drinking water and water for their crops, easy travel and trade with other people. So those are the physical factors that play a role in where the world's population is distributed and now let's consider the other major category that affects population distribution, namely human factors. The first human factor to know is. culture. Like people may choose to live in a place because that place is somehow important to their culture. You know, they live here because they feel like they belong. For example, both Jews and Muslims feel like they have a right to the land of Israel and Palestine because they have ancient cultural attachments to them. But don't worry, those rival attachments to the same land haven't caused any geopolitical problems in the world. No, they've caused a lot. It's a real problem. Anyway, the second human factor that determines how population is distributed is economics. People tend to settle where they're confident that they can make a living, you know, where resources and jobs are abundant. And that means economics can often be a major reason for migration as well. For example, those who are The government responsible for the African slave trade had significant economic incentives to move millions of enslaved Africans from their homes in the Americas starting from the 15th century. Also a major factor in the large waves of immigration in the United States during the 19th century was that jobless Europeans were looking for work, and they found it. in America. So they packed up their bags and they migrated. Okay, now a third human factor for population distribution is history. And what I mean is, how populations were distributed in the past can have a strong influence on how they are distributed in the present. For example, over half of all black Americans live in the South, and that has a lot to do with the history of slavery in America. Almost half of all Asian Americans live in the West because their ancestors migrated from Asia and settled there. Okay, now a fourth human factor influencing population distribution is politics. So you know, if a group of people don't like the politics in their region, maybe they move elsewhere. And this was the case for a great deal of the immigrants coming to America from Europe in the 19th century. A lot of them weren't exactly fans of the tyrannical turds running things back home, so they migrated here to America, and you know, that was voluntary. But also people can be forced to move because of political regimes. For example, in 1975, the totalitarian Cambodian regime known as the Khmer Rouge forced millions of Cambodians from their capital city into the rural countryside. Okay, so those are all of the high-level reasons why the arts population is distributed. But now we need to talk about a related concept, namely population density, which is a measure of how many people occupy a given unit of land. If that sounds like the same thing I was just flapping my mouth hole about in the last section, it's not. In the last section, I was flapping my mouth hole about population distribution, which asks where do people live. Here we are talking about We're talking about population density, which asks how many people live here. So don't get confused with the two, I know you want to! But don't. So when it comes to calculating population density, you need to know the three methods geographers use, and you need to understand the value of different calculations for answering questions about the pressure those populations exert on their land. The first kind of calculation is called arithmetic density, which is the total population divided by the total land area. And that's all the land, even the land that's uninhabitable. Because this measure of density includes every square inch of land, the result doesn't necessarily tell the whole story. For example, Taiwan has one of the highest population densities in the world, but three quarters of its people live on one. third of its land area. So arithmetic density does not account for this, and that number might lead you to assume that the population is distributed evenly across Taiwan, which they are not. Okay, now a second kind of calculation is physiological density, which is the total population divided by the total amount of arable land. Waterable land? Arable land. It means land that can be used for agriculture. So this is a measure that demonstrates whether a population is able to feed itself. Like, is there enough arable land to grow enough crops to feed everyone's mouth hole? And the higher the physiological density, the more pressure will be put on farmland to produce enough food, and the lower the number, the less pressure on the farmland. For example, the United Arab Emirates has about 32,000 square miles of land and almost 10 million people as of 2020. But only about half a percent of that land can grow food, because you know, it's in a giant stinking desert. So this is a good good example for us to compare the different insights generated by different calculations of population density. So the arithmetic density of the UAB gives us 312 people per square mile. And hey, that doesn't sound so bad, does it? But when we consider how much farmland is available to feed all those people, which is to say we calculate the physiological density, we get over 6,000 people per square mile. That's a lot of density, Tony. Okay, now the third method of calculation you need to know is agricultural density, which is the total farmers in a place divided by the total arable land. So here, a lower number means less farmers available to grow. grow food. But that doesn't necessarily indicate that everyone in that place is going to starve. Especially in wealthy, industrialized countries, a lower agricultural density means that farming has become mechanized. So yes, there are fewer farmers, but that's because they can use those big honking machines to do the farming for them. On the other hand, a high agricultural density usually means that many farmers are subsistence farmers which means they grow only what they need to survive and they don't sell it on some distant market. Now it's important to know that none of these calculations tell us the whole story alone, but if we get them in a big equational hug, then we start to get a complete picture of population density and its implications for how people put pressure on their land. But, okay, who cares? Why does calculating all this even matter? Well, it matters, my young pupil, because population distribution and density can significantly affect four processes that you need to know. First, density and distribution affect political processes. For example, here in America, a census is taken every ten years, and once they find out where all the people live, seats are gained or lost in the House of Representatives, and that can shift the balance of power in Congress. Second, density and distribution affect economic processes. Population density numbers determine how money is spent for both private and public services. So if an area is growing rapidly in population, businesses have more incentives to open stores and offices in those locations, and the opposite is true in places with decreasing populations. And governments also allocate money for infrastructure projects like roads and bridges based on whether these places'populations are growing or declining. Third, density and distribution affect social processing. And these calculations can determine how accessible public services like schools or hospitals are to a given population. Like, it's way more cost-effective to build a hospital, for example, in a densely populated area than in a sparse. So you know, if you live out in the country and you wake up with a kidney stone the size of a baseball, well, it's gonna be a long night. And fourth, density and distribution affect the health of the environment and access to natural resources. You see, as a population grows, more people need to eat and drink, and that means more pressure on the land and water sources. And central to this concern is the question of the Earth's carrying capacity, which refers to the maximum population an environment can support. And geographers fight about this like children fighting over who gets to dig up all the gyroids after it rains in Animal Crossing. And they debate because so many factors come. complicate the potential carrying capacity, including climate, agricultural productivity, technology, etc. Some studies say that the Earth's carrying capacity is 500 million, while others say it's over a trillion. But determining carrying capacity is even more complicated when you consider that not all people use the same amount of resources. Middle class Americans, for example, use far more resources than they need to survive, and that decreases the Earth's carrying capacity. Like, if everyone used only what they needed in the carrying capacity, might be easier to determine. But, you know. They don't. Okay, so we've talked about how population is distributed and how dense it can be and how that- calculate population density and why all that matters. So now let's turn the corner and talk about population composition, which is the measure of certain characteristics of a population like age, race, gender, etc. There are two very important elements of population composition you need to know. First is the age structure of a population, which is an organization of population based on age groups. So people like me in my early 40s would be an age group, and then people like my grandpappy who was older than dirt and dog ears is another group. Son, I may be old, but I can still wear you out. Yep. That's true. Anyway, knowing how many people fit into different age groups enables geographers to draw conclusions about whether a population is growing or stable or declining and we'll talk more about that in a minute. Now, one very important- Part of the age structure that you need to know is a population's dependency ratio. Now dependents are people who, you know, depend on others to survive, usually children under the age of 15 and elderly people over the age of 65. In other words, these are people who are generally not working to support themselves. And knowing this ratio is helpful in figuring out the pressure put on the working age population to support other non-working dependent groups. So think about it this way. Suppose these two parents both work, and together they make $100,000 a year, and they only have one child or you know, one dependent, this would be a low dependency ratio. And then this family over here makes the same amount, but they have five children, this will be a high dependency ratio $100,000 is going to go a lot further and providing for the needs of that one child than it will for five children. You smell what I'm stepping in? So that becomes a very important measurement for a given population at national, regional, and local scales to determine current and future levels of productivity in the working population. A higher dependency ratio indicates fewer working-age people supporting more dependents, while a lower dependency ratio indicates more working-age people supporting less dependents. And just for poops and giggles, you should know that the dependency ratio is calculated by taking the number of people in the dependent age group and dividing by the number of people in the working age group, multiplying by a number of people. Okay, now the second element of population composition you need to know is the sex ratio, which represents a comparison of males to females in a population. And depending on the scale we use, the sex ratio can be different. On a global scale, the sex ratio is about 101 men to 100 women. But zoom into a single continent like Europe and the ratio is 95 to 100. Or zoom in further to just one country and we'll choose China for funsies and the ratio is 110 to 100, and that's a result of their one-child policy, but we'll talk about that later. Here are some key tools geographers use to compare the age structure. and sex ratios is the population pyramid. And oh- Baby, are you definitely going to see this on your exam. So let's talk about how to interpret it and why it's important. So here on this global pyramid you see five year age increments on the Y axis and male female percentages on the X axis. So this tells you that out of the world's entire population in the 50 to 54 age range, 2.9% are male and 2.9% are female. Easy peasy lemon squeezy. Now the reason population pyramids are such powerful tools is because depending on the shape of them they can tell us whether a population is growing or declining. Let me show you the four typical shapes that illustrate those trends. This shape illustrates a population. population in rapid growth. You see that wide base? That means that there are way more young people than older people. And this shape often occurs in developing countries where the birth rates are high and the lifespan is shorter, like for example in the Democratic Republic of the Congo. So a population in rapid growth will need to focus many of their resources on providing for the needs of children, like, you know, education. Now a population in this shape is still growing, but it's an indication of slow growth. Here the birth rate is only slightly higher than the death rate. It's still a pyramid, but the base is much narrower. A good example here is China, and the narrow base shows the result of their one-child policy that I mentioned earlier. Then there's this shape which indicates stable growth. Here the birth and death rates are similar and there's a roughly even distribution throughout the different age ranges. And a good example of stable growth is the United States. And finally, this shape here is kinda bad news because it indicates population decline. Here the death rate is higher than the birth rate and that's why the base is narrower than the top. Germany is a good example here, and for populations in this kind of shape, they're gonna face challenges like labor shortages and decreasing demand for consumer products. products. Okay, be honest, have I told you more about population than you ever wanted to know? Yep. Well, don't worry because there's more. So now we need to talk about population dynamics, which is all about how geographers study the trends in population growth or decline. And for that they consider three areas, fertility rates, mortality rates, and migration. Now the fertility rate is the measure of a population's ability to have children, and that is important because, to paraphrase the notorious B.I.G., that great philosopher of population phenomena, Mo'Baby's Mo problems. And to be fair, you know, less babies, less problems, but it's not as catchy. Anyway, knowing the fertility rate is useful for governments, for example, who want to know whether their populations are growing or remaining stable or declining. With this information, they are better able to plan and allocate funds for infrastructure projects and education and healthcare. And I know what you're thinking, but Heimler, how do you measure the fertility rate? I got you. First is the crude birth rate, which is the number of births per thousand people in a given year. So a simplistic example would be this. If you have a population of a million people and 10,000 babies are born, then both get divided by a thousand and you can get a crude birth rate of 10 per thousand. This measure is useful for predicting future population growth. So for example, the lowest crude birth rate in the world is 10. The highest crude birth rate in the world right now is Europe, and the highest is in Africa. Now, a potentially more accurate measure of a population's growth or decline is its total fertility rate, which indicates the average number of children one woman will have during her childbearing years, which is roughly age 15 to 49. Now this measure of fertility is more accurate than crude birth rate because it only considers the part of the population who are capable of bearing children. Additionally, a country's total fertility rate is often a signal of that country's access to healthcare and medical services. What I mean is, a lower total fertility rate tends to occur in wealthier countries where access to healthcare is more important than the total fertility rate. healthcare and family planning services are abundant. In those places, it's easier to avoid unwanted pregnancies. And the opposite is true for less developed countries with higher total fertility rates. Now you should know that a TFR of 2.1 is the rate at which a population will remain stable because last time I checked it takes two people to have a baby and so they need to have at least two babies to replace themselves in the population. So Europe's TFR as of 2020 was about 1.5, which means they're experiencing population decline, whereas Africa's was 4.3, which means population growth. Okay, so that's fertility rate. Now, the second measure geographers consider when studying population growth and decline is mortality rates, which indicates a population's rate of And here there are two varieties of measurements to know. First is the crude death rate which measures the number of deaths per thousand people. Now at a global scale the crude death rate is currently about 8 per thousand. But in 1960 it was 13 per thousand and it has steadily declined since then. So that means that worldwide people are living longer on average. And that's great because that means I'll be around much longer to hurl sassy AP videos onto the internet for you marvelous people. Now the question is, why are people living longer today than they have in the past? Well, in general, people are experiencing longer lifespans because of better nutrition, better quality medical care, and expanded access to clean water. So put all those factors in the pot and baby, you've got a stew that smells like an increased life expectancy, which is how long an average person is expected to live. And again, scale matters. Like in some wealthy developed nations, the life expectancy is 80 years, while in many developing nations it's more like 50 years. Okay, another related measure of population growth and decline is infant mortality rate, which is the number of children who die before they reach the age of one per 1,000 live births. I said before that a low crude death rate can be explained by better access to health care, but the infant mortality rate is often a better indicator of a country's access to health care than the CDR is. In places with a high infant mortality rate, they tend to have less access to life-saving interventions and medicines to help babies survive infancy. And in places with a low infant mortality rate, they tend to have more access to health care. Okay, so those are the kinds of measures you need to know, so let's start putting them together. Geographers use both the crude birth rate and the crude death rate together when they want to study change. changes in populations. So take the CBR and subtract the CDR and that gives you the rate of natural increase for a population. So if a population has a crude birth rate of 20 births per thousand and a crude death rate of 10 deaths per thousand, then the rate of natural increase will be 10, which, you know, is 20 minus 10. In this case, the rate of natural increase is positive, so the population is growing. But if the RNA is negative, then the population is declining. Now, to be clear, this measurement of growth or decline is only about a population's births and deaths. deaths, but those aren't the only ways a population changes. Anyone know any other ways that populations can grow or decline? Anyone? Anyone? Oh, me? Ah, migration? That's right. So the RNI says precisely nothing about population increase or decline due to migration, and we'll get to that in a minute. But for now, just understand that even if a country's RNI is steady or declining, they might still see an increase in population due to migration. Now another reality geographer study with reference to population is the doubling time of populations, which is exactly what it sounds like. Given the current population growth trends, how long will it take for that given population to double? And this number varies according to the crude birthing, death rates, infant mortality rates, and the rest. So, Ethiopia's doubling time will take 20 years. 27 years. Why? Because it's in the rapid growth phase and it won't take long to double that population. But the United States will take 233 years to double because it's in the stable growth phase. Okay, now that we've talked about the fact of growing and declining populations, now we have to consider the various factors that influence fertility, mortality, and migration. And the first influences are social and cultural factors. For example, different cultures have different expectations for women, which can play a significant role in fertility rates. Some cultures have strict gender roles and expect women to stay home, raise large families, and make their husbands sandwiches, which can lead to a higher fertility But in other cultures, women have more freedom to pursue education and careers, which can often lead to fewer births, leading to a lower fertility rate. And second, political factors influence fertility, mortality, and migration. Governments monitor their population growth carefully and can encourage or discourage births. And we already talked about one example of this, namely China's one-child policy enacted in the 1970s. During that time, the Chinese government was getting all sweaty as they looked at the explosive growth of their population, because, you know, Too many mouth holes, not enough food to feed them. So they enacted the one child policy to restrict their population. On the other hand, when governments see that their population is declining, they can encourage families to have more babies by passing laws guaranteeing access to health care, more generous maternity or paternity leave from work. But third, there are also economic factors that influence fertility, mortality, and migration rates as well. Birth rates often decline during economic downturns when people are worried that they don't have enough means to care for more children. But when the economy is good, people will be making babies because they're optimistic about the future. So So look, here you see that during the Great Depression here in the United States, the total fertility rate in the U.S. was a real low. Like, nobody had any money, so fewer babies were born. But look, here's the baby boom, which coincided with a wave of incredible economic prosperity, and then the economy started tanking again about here and, you know. You get it. But economic factors can also determine rates of migration. For example, during the 19th century the United States economy was in general doing very well while Eastern and Southern Europe's economies were, to use the technical geographical term, a turd halfway to being flushed. And that economic reality led to massive migration to the United States of European immigrants looking for work. Okay, now everything we've been talking about thus far is all about measurements and percentages and precise mathy mathy stuff. But I can see it in your eyes. You want to get a little more theoretical about population dynamics. And that's great because that's exactly what we're about to do, y'all. And I want to explain. explain to you two theoretical models that attempt to explain population growth. First is the demographic transition model, which is a graph that attempts to explain the growth and changes in human population. population over the course of history by considering birth and death rates. But before I explain what all this means, you need to remember that this model was created to explain European and American populations, and that means it might not be as useful for explaining population realities in other areas of the world. Now, you will absolutely see this on your exam, and it looks all kinds of confusing, but just stick with me and I will help you understand. So the basic function of this model is to chart how crude birth rate, crude death rate and the rate of natural increase change as the society passes through these different phases of history. So stage one is called the high stationary phase and a population in this phase is pre-industrial and agrarian. Now agrarian means that these people are mainly farmers and pre-industrial means that everything they needed to live like you know clothes and tools were made by hand and not machines. So in this phase you can see that the birth rate and the death rates are both high which means that they kind of cancel each other out. Like a lot of people are being born and a lot of people are dying and so everything is basically even. And that leads to a stable population that basically remains steady or growing a little or shrinking a little. Now, agrarian people tended to have a lots of babies because they needed help on the farm. Well, son, you're four years old now and That goat ain't gonna milk itself. But all those babies are not going to lead to significant population growth in this stage because poor nutrition and disease meant the average lifespan was somewhere in the 30s, making the death rate high as well. And as the world currently stands, no present nation is in stage one. But then we get here to stage two. which is known as the early expanding stage, which corresponds to a population's entry into industrialization. Now we're going to talk all about industrialization in Unit 7, but for now you just need to understand that the Industrial Revolution marked a transition from an agrarian society to a modern mechanized society. So here the birth rate remains high, but the death rate begins to drop precipitously due to advances in science and new medicines and better nutrition, vaccinations, etc. So that led to a dramatic increase in lifespan. People are living longer. That's still a lot of babies are being born, and so this gap right here indicates a population explosion. And then we move right along to stage 3, which is the late expanding stage. In this stage, populations are continuing to industrialize, medicines are getting better, more people have access to nutritious foods, education becomes more important, etc. And under these conditions, the birth rate begins to decrease sharply. And the reason is that as more people have access to education and get further away from life on the farm, children are not necessarily an asset for work. But even so, there are still more births than deaths, so in this stage, the population grows slowly. many developing nations are in this stage. And then moving along to stage 4, we have the low stationary stage. And at this stage, a country is considered to be completely industrialized. And here you can see that birth and death rates are similar, which leads to a slow population growth or stabilization. And when a population arrives in this stage, it has new worries about an aging population and all the issues that come with it. And today, most developed nations are in this stage. Now when this model was first introduced, it only had four stages. But recently a potential fifth stage has been added. Geographic intrigue? This stage is called the natural decrease stage. So in every stage before this, populations were either stable or growing. But here we get the ultimate wah-wah as the death rate exceeds the birth rate and the rate of natural increase begins to decline. Now some European countries along with Japan are now in this stage. But remember, the populations of these countries might still grow through migration, so, you know, Fingers crossed. So again, this is a theoretical model that traces how populations grow and decline through specific periods of historical development. And the key theme of this model is a country's level of industrialization. But there's another model you need to know that looks at population growth and decline not through the lens of industrialization, but instead through the lens of disease. It's called the Epidemiological Transition Model, and this model focuses on the death rate and tries to explain why the death rate changes over time. Now, in case you don't know, epidemiology is the study of how diseases spread. So, maybe think of this model as the nasty germ transition model. Anyway, in this model, stage 1 is known as famine. In this stage, people can die from dang near anything. Infectious or parasitic diseases, bear attacks, whatever. If it's lethal, you can die from it in this stage. And probably the most dramatic example of populations in this stage is the spread of the bubonic plague, otherwise known by its cuter, more playful name, In the 13th and 14th centuries, this disease spread along trade routes throughout Afro-Eurasia and killed a fourth to a half of any given population. Therefore in the famine stage, the death rate is high and life expectancy is low. The population can grow, but usually it grows in bursts and is not sustained over time. Stage 2 is known as the receding pandemic phase, and here life expectancy increases significantly from about 30 to about 50 years old and the death rate begins to decline. Populations enter this phase when they begin to have access to improved sanitation and nutrition and medicine, all of which helps fend off the great plagues killing humanity. But don't celebrate yet because people are still dying by the metric b- buttload in this phase, and here people are mainly dying from pandemics, which are diseases that are spread throughout regions in the world. And this is especially true because people in this stage often are living much closer together in cities, which is where the nasty germs can spread real easily. And then we move right along to stage 3, which is known as the degenerative and human-created diseases phase. Now here the death rate is still low and life expectancy continues to increase. Now you'd think that'd be a good thing for people to be living longer, like puppies and rainbows as far as the eye can see. But longer life brings other problems with it, especially diseases associated with old age, like heart disease and cancer. Okay, now stage four is called the delayed degenerative disease phase. And this is the stage where life expectancy is at its highest. Here, medical technology advances significantly to address diseases that are so common that it's hard to even imagine what they would be. associated with aging. So you know for heart disease we get bypass surgery and for cancer we get chemotherapy etc. And dang it, I wish I could tell you that's where we're all headed. Better and better medical technology and longer and longer life span. But this model is here to crush any hope you have because we also have stage 5 known as the re-emergence of infectious disease phase. Yeah, it's great that we developed all those medical technologies to fight off diseases, but here infectious and parasitic diseases develop immunity to our drugs and our antibiotics and then they come right back. Therefore those diseases become a deadly threat yet again and life expectancy Okay, now the main critique of the epidemiological transition model is that it oversimplifies the causes of population change due to diseases. In other words, this model doesn't account for differing historical periods or locations. Additionally, the ETM doesn't account for poverty as a cause of the spread of disease, which is a major omission. Poverty is one of the most significant causes of shortened lifespans and probably does a better job explaining differences in death rates and the spread of disease. So there you go, if you're at a party and you get into an argument about the efficacy of the ETM to explain population patterns, well now you're well equipped to hold your own. Or maybe that's just the parties I go to. Anyway, moving on. Okay, now let me introduce you to yet a third theory on population growth and decline, namely the Malthusian theory. Now Thomas Malthus was a cheery British demographer who lived in the 18th century and looked around at the European population trends and was like, yep, everybody's gonna die. He was a fun guy. Anyway, his worries were centered on the dramatic increase in the population that he was observing, which was happening for two reasons. Birth rates were slowly increasing, but thanks to advances in medicine, the death rate decreased sharply. So not only were there way more infants surviving childhood, but people were now living healthier and longer lives. So you and I look at those developments and we're all like, thumbs up! But not Thomas Malthus. He looked around at people living longer and not dying from disease and was like, Oh, this is terrible. Anyway, the reason these developments worried Malthus is because he observed that while the population of Europe was growing exponentially, the food supply was only growing arithmetically. And I know that doesn't make any sense to you, let me say it differently. He worried that if the population kept expanding as rapidly as it was, then by 1800 there would be more people than food to feed them, which would result in massive famines and plagues, which would be the only way to decrease the population. So Malthus summoned his inner Thanos and argued that people should delay marriage and have less children so that everyone wouldn't die. Now, spoiler alert, Malthus was wrong. From our vantage point a couple centuries later, we can see what Malthus could not, namely that new technologies like mechanized farming and chemical fertilizers enabled the growth of the food supply to keep up with the population. So sorry Thomas Malthus, you're basic. Okay, now let's leave all the theoretical stuff behind and talk about consequences of population growth or decline. Like why does all this matter and to whom does it matter? Well first, population data matters too. In some cases, governments can attempt to influence the population growth, you know, the rate of natural increase of their populations, and they can do that in several ways. First, they can introduce antinatalist policies, which are policies intended to decrease the number of children born. And usually this is done because governments are concerned that their populations are growing too fast for their resources to keep up. I'm looking at you, Malthus. And the most famous antinatalist policy was, once again, China's one-child policy. Now on the other side of the spectrum, governments can introduce pronatalist policies, which are policies intended to increase the number of children born. increase the number of babies born. And usually governments do this because they're worried about the effects of an aging population. More specifically, as the population ages and stops working, there may be a gap in working-age people to fill necessary jobs to keep the economy afloat. And that is a No bueno. So pro-natalist policies can include generous parental leave from work and free day care and other means to decrease the expense of raising children. And then third, don't forget that populations can grow or decrease because of migration, and so governments can also introduce immigration policies which either allow more immigrants in or restrict the flow of immigrants. For example, in the 1950s and 1960s, as Western Europe was recovering from World War II, they experienced an economic boom. However, because of the significantly decreased population due to the staggering amount of immigrants, the population grew. deaths in the war, several nations passed policies basically inviting immigrants to come live and work there. Okay, let's talk about the ladies. Now over the last few decades, geographers have focused more and more on women and their role in the world, especially their role with respect to fertility rates. And what's been most interesting to notice is that as women's status is elevated and they have more access to healthcare and contraception and education, fertility rates tend to decrease. On the flip side, in places that uphold more traditional gender roles, which is to say women are mainly seen as the bearers of children, those women tend to have more babies. But you need to know that there are basically three ways that women's roles can be elevated in a population. And when women are elevated, it has a significant impact on the fertility rate. First, access to education. Pretty universally, when women have access to more education, they tend to have fewer children. And to help you remember that, demographers call this the more books, less babies principle. And that happens for several reasons. One reason is that educated women tend to be more skeptical about cultural norms that dictate how many babies they should have. Okay, now the second way women's roles are elevated is by access to family planning, which include medical technologies that can help women have more control over when and if they get pregnant, and therefore that lowers the fertility rate. And here you have medical technologies like the birth control pill or intrauterine devices. And then the third way women's roles are elevated is by increased access to employment. As more opportunities for women have opened in the workplace, especially over the course of the 20th century, century, many women delay marriage and childbearing in order to focus on their careers. Now it's also important to know that the changing roles of women ...also affect mortality and migration, and first let's consider mortality. Now, as I mentioned, as women have more access to education, health care, and family planning, they do have fewer babies. But the fewer babies they do have are more likely to live. In other words, as women are elevated, the infant mortality rate decreases. let's consider the effect of women's roles on migration. And here let me introduce you to my boy Ernst Georg Ravenstein. He was a 19th century geographer who developed 11 laws of migration to explain how and why and under what conditions people migrate. Now you don't need to know all these laws, but law six says that women are not allowed to migrate. women are more likely to migrate within their home country, while men are more likely to migrate to other countries. So in countries where women have more autonomy, they are often the chief movers when it comes to migration, and mostly it's rural to urban migration. Okay, so now let's focus a little more on the issue I mentioned earlier, namely the causes and consequences of an aging population. First of all, what in the fresh heck is an aging population? Well, basically it's a population in which the dependency ratio is increasing, and they tend to have a lower total fertility rate also, somewhere below 2.1. So in terms of a population pyramid, aging populations look like this. look like this. The middle cohorts are larger than the lower cohorts. So basically an aging population is determined by the birth rate, the death rate, and longer life expectancy. So those are the causes of an aging population, and now what are the consequences? And I can think of three. First, you have political consequences. As the population gets older, they can have a significant effect on the balance of political power in a country. For example, in the United States, the most reliable voters are those over the age of 65. So while the 18 to 25 year olds are busy trying to become ticked off, they're also trying to TikTok influencers, those retirees are in the voting booth making sure their interests are protected. And that means that in general, as a population ages, the policies passed by Congress will reflect the interests of senior citizens, the most significant of which is social security and healthcare. But second, there are also social consequences of an aging population, like for example providing care for the elderly. You see, the more a country industrializes, the more likely a society is defined by the nuclear family instead of multi-generational households. And as you may know, nuclear families move all over the dang place, away from the older generations. lived close, then the younger members of the family could care for the older members of the family when that time comes. But in the age of the nuclear family and increased migration, more elderly people are moving into retirement and nursing facilities to get the care that they need. A third, there are economic consequences to an aging population. So as a population ages, they pay less in taxes, and if a population is made up of a majority of older folks, then that presents a big, fat economic problem. For example, here in the US we have Social Security, which provides monthly payments to retired people. And do you know who pays for the current generation of retired people? people of working age. So look, you can see the problem. There are a lot more people retiring than there are working, and that is a major economic... problem created by an aging population. In fact, the prediction is that the Social Security Fund will be depleted by 2031, so by the time I retire, all that money I've been putting into that fund since I was 16 years old will be gone, and I'll go have to live in a van down by the river. Okay, enough of that. Now let's get to our last major section, which is all about migration, and I reckon we ought to start by talking about why people migrate. But first, let me clear something up so you don't get confused. You're going to hear me use two words that kind of sound the same, but they are not. Immigration and emigration. Immigration refers to people coming into a country, while emigration refers to people leaving a country. Immigration in, emigration out. We good? Now, why do people migrate? Well they migrate because they experience either push or pull factors. Push factors are negative experiences that push people out of their country. So maybe a war or persecution pushes refugees out of their country to find shelter in another country. Or maybe it's famine or a natural disaster like Hurricane Katrina in 2005, which sent around a million Louisiana residents seeking shelter in other states. On the other side, people migrate because of pull factors, which are positive factors that attract migrants to a new place. Maybe- pulling them out of their home. So for example, pull factors can include new job opportunities or seeking freedom under another country's more stable government. And hopefully it's obvious, but when people decide to migrate, they're usually experiencing a combination of push and pull factors, like they rarely occur in isolation. So for example, during the Irish potato famine in the 19th century, millions of Irish poor were starving. So you know, that's a push factor. So as a result, many of them migrated to the United States because there was food and work over there. That's a pull factor. All right, you mowing what I'm growing? Good. Okay, so people migrate because they experience significant push and pull factors. But when they make the decision to leave for their new destination, they will almost always experience intervening obstacles and opportunities. Intervening obstacles refer to challenges that they must overcome in reaching their desired destination. On the other hand, sometimes migrants experience intervening oppor- opportunities, which can be anything that they encounter that changes the original destination of their migration. Now to further complicate things, all of these push and pull factors and intervening phenomena can be categorized under five headings. You've got cultural, demographic, economic, environmental, and political. And let me explain each of these with some examples very quickly. In the cultural category, persecution can be a push factor, as it was during the partition of India. After World War II, the northern part of India, which was a Hindu majority, was sectioned off to create Pakistan, which would be a Muslim majority nation. So Muslims who no longer felt welcome or safe in India, India migrated north to Pakistan while Hindus migrated south to India. And that became a horrible mess and the loss of life during that event was staggering. Now in the demographic category, rural people may migrate because they lack access to healthcare services. Or urban people may migrate away from the city because of the dense population there and there are just not enough jobs for everybody in that city. And then in the economic category, people tend to migrate to find jobs to support themselves and their families. A good example here was the Bracero program, which was an agreement between the Mexican and US government during World War II. And because the US was busy moping, Globalizing to blow people up in distant lands, agricultural and transportation jobs were going unfilled. And as a result, over 4 million Mexican workers migrated across the border to fill those vital roles. Now in the environmental category, in addition to natural disaster displacement, people may migrate because the climate of a region is more desirable than their current climate. For example, Florida is home to the largest population of retirees in America, many of whom migrated to avoid the butt-cold winters of the American North. Then in the political category, war is a major political push factor that sends many migrants seeking safer conditions elsewhere. For example, the Syrian Civil War, which began in 2011, 11 has been responsible for the emigration of more than 5 million Syrians from their homeland. Okay, now there are two major categories of migration that you need to know. There's forced migration and voluntary migration, and each of those are exactly what they sound like. Forced migration occurs when people leave their homes against their will. Probably the example you are already familiar with is slavery. But slavery isn't the only kind of forced migration. As I mentioned before, people often flee their country because of war or persecution. For example, hundreds of thousands of Armenians fled their homes during the Armenian Genocide in the first part of the 20th century. So people flee their homes because of war. who migrate for these reasons are known as refugees, and refugees have the right under international law to seek asylum or protection in other countries. But there's another group of migrants known as internally displaced persons who leave their homes for similar reasons, but they just go to another part of their own country. So forced migration is always ugly and creates all sorts of human crises. But let's brighten things up a bit and talk about voluntary migration, which occurs when people leave their homes because they want to. And because one, geographers love to categorize things and two, they hate you. There are seven categories. There are two categories of voluntary migration you need to know. The first category of voluntary migration is transnational. These migrants, while they live in the place that is not their home, retain strong ties to their culture and their family back home. It's like they live in two cultures at once across national boundaries. So one major way this often works out is this. If the migration occurred to find work, then the transnational workers will often send money home to the people they left behind, maintaining that relational connection across distance. The second category of voluntary migration is called transhumans. This refers to migration by people who move not because of unfa- foreseen push and pull factors, but because movement is their way of life. And although there are fewer and fewer of these groups of people today, nomadic peoples who move from one area to another would fit this category. Now, the third category of voluntary migration is called internal migration, which refers to people who migrate within the borders of a country. Now, according to Ravenstein's laws of migration, most migrations occur over shorter distances because, you know, there are less intervening obstacles encountered over short distances. Makes sense. Stay with me now. The fourth category of voluntary migration is called chain migration. The idea here is that one group of migrants can often cause other migrants to follow them. So the first stage of chain migration might be a group of migrants who settle elsewhere because of various push and pull factors. And then once they've established themselves in that new location, they stay in contact with those they've left behind. Then after some time passes, if they have found a better life in their new destination country, the people they left behind will often migrate and settle with them in the same place. So back to the huge Irish immigration to America that we talked about earlier, this is is a good example of chain migration. The first wave of immigrants was pushed out of Ireland by famine, and even though they were no longer starving in America, they did face a pretty rough reception. But over time, as Irish immigrants became more and more part of American society, more Irish people immigrated and found their new home much more accommodating. Okay, the fifth category of voluntary migration is called step migration. The idea here is that a migrant's journey often occurs in stages, or steps, and not all at once. So a group of migrants may plan to arrive at this destination here, but then they encounter intervening obstacles or opportunities as they often do. As a result, they may choose to settle in villages and cities along the way until they can make the next step and leave for their ultimate destination. The sixth category of voluntary migration involves people called guest workers. This is a temporary form of migration in which migrants travel to a new country to work for a specified amount of time. I already mentioned the Bracero program earlier, which is a good example of that. And then finally, the seventh category of voluntary migration is known as rural to urban. Now this is the movement of people from sparsely populated countryside to densely populated urban centers. And this particular kind of migration has been increasing ever since the rise of the Industrial Revolution. Alright, well give yourself a good slap in the face to wake up and let's push through this final section to talk about the effects of migration. Those effects fall into three categories, political, economic, and cultural. First, migration can have significant political effects. For example, when people migrate can change the distribution of political power as it did here in the United States in the mid 20th century when a bunch of people from the North and Midwest migrated to the Sunbelt states. But immigration can also have negative political effects. So when immigrants arrive in large numbers, it can sometimes make the native-born people who live there a little cranky, and as a result the government may pass laws restricting immigration. Probably the most notorious example of this in American history was the Chinese Exclusion Act of 1882. You see, in the 19th century, Chinese immigrants to America surged as jobs in the railroad industry opened up. But native-born Americans began blaming the Chinese immigrants for keeping wages low and taking their jobs. So the Chinese immigrants were forced to leave the country. And I'm pretty sure the only reason we got those jobs to begin with is because you guys didn't want it. Regardless, the result was that Congress passed the Chinese Exclusion Act, which enacted a 10-year ban on Chinese immigrants. So yeah, I'd say that had a negative effect on immigration. Second, migration can have significant economic effects, and these can be felt both in the destination countries where these migrants are going and in their countries of origin, you know, where they are leaving. The migrants'destination countries benefit from immigration because immigrants often come seeking work. Additionally, immigrants will often accept jobs at lower wages in sectors where native-born people are less- willing to work. Today, two of the biggest of those sectors are agriculture and construction. This arrangement can be extremely helpful to a country with an aging population because more workers in the economy decreases the dependency ratio. Oh man, we're just tying all these concepts together. Feels good, doesn't it? But the migrants'countries of origin also feel the economic effects. With working age people leaving, more jobs are open for those who remain behind. Additionally, immigrants often send money back to their country of origin, and the term for that money is remittances. And as far as the role of remittances in the world economy, they're no joke. According to the World Bank, in 2022, over $630 billion in remittances circulated between immigrants and their families and friends back home. But flip that same coin over to the negative side, and we see that since the majority of migrants who leave a country are of working age, then that can create a problem. problem if there aren't enough people to fill the jobs that they left behind. That can create slow growth for the country of origin's economy. And third, there are cultural effects of migration. In destination countries, a significant cultural effect is the introduction of the immigrant's culture, their language, their religion, their music, etc. For example, as a result of the large influx of Mexican immigrants to America since the Bracero program, Mexican food is a staple item in the United States. And I have to be honest, I ain't mad about it. Now in countries of origin, the cultural effects of migration are often connected to economic benefits. Because of the prevalence of remittances, families left behind in the country of origin can often afford a better lifestyle than they otherwise could. But on the negative side, the social structures in the countries of origin can be strained by migration. Families can be broken apart when one of the parents, usually the father, departs looking for work elsewhere, and that's rough on the family. In this case, the dependency ratio increased, putting more stress on the working population there. Okay, now to keep reviewing for Unit 2, click right here and keep watching. Click here to grab my AP Hug Heimler Review Guide, which has everything you need to get an A in your class and a 5 on your exam in May. I'll catch you on the flip-flop. Heimler out.

So if you're ready to get them brain cows milked. Let's get to it. Now let's begin in the beginning and talk about population distribution. So when we talk about population, we're talking about groups of people.

Population distribution refers to the pattern of human habitation on the Earth's surface. If every single person were spread out evenly over the Earth's surface, each of them would have about two football fields on which they could live. And, you know, that'd be nice, but the Earth's humans are not, in fact, evenly distributed. Some people live isolated and miles from other humans, while others live packed together tighter than canned yams, which, you know, can be pretty tight.

Anyway, we need to understand. why the differences in population distribution exist, and there are two basic factors. But before I tell you what those are, let me remind you that if you want to get an A in your class and a 5 on your exam in May, then click the link below and have a look at my AP Human Geography Heimler Review Guide. This thing has exclusive unit review videos that are not here on YouTube.

They have note guides to follow along with those videos, practice questions, a full practice exam, a free demo of my AI Heimler Bot which is going to help you answer any question you have and score your responses. It is the fastest and most comprehensive way to study for this course, so check it out. And now back to the video.

Back to the two factors that explain population distribution. First are physical factors. You see, because humans depend on the environment for their survival, the various features of the earth often determine where people live.

So one physical factor that affects population density is climate. People tend not to live in high numbers where the climate is harsh. You know, if it's too wet or butt cold or too dry or whatever, less humans tend to live in those places. For example, most of the population in Australia is distributed near the coast.

coast where the temperatures are more temperate and almost nobody lives in the center where it's dry and hot enough to fry eggs in the dirt. So for the most part, humans love to live in the mid-latitudes, between 30 and 60 degrees from the equator because the temperature is milder and there's a decent amount of precipitation. Okay, now a second physical factor in population distribution is landforms. In general, humans like to live in lowland areas because in those areas it's easier to build and easier to farm. Mountainous areas, on the other hand, tend to be sparsely populated.

Hey, can I borrow some sugar? And that's not hard to understand. Higher elevations bring... bring challenges to human life like nasty cold temperatures, minimal food, and lack of breathable air.

But this is only true in the middle and higher latitudes. In places close to the equator, some mountainous regions can be highly populated precisely because they're cooler and more temperate. Okay, now a third physical factor that affects population distribution is water.

From the dawn of human history, human settlements have gathered around bodies of water, either rivers or oceans or lakes. Again, not hard to understand. These bodies of water provide people with what they need to live, like drinking water and water for their crops, easy travel and trade with other people.

So those are the physical factors that play a role in where the world's population is distributed and now let's consider the other major category that affects population distribution, namely human factors. The first human factor to know is. culture. Like people may choose to live in a place because that place is somehow important to their culture. You know, they live here because they feel like they belong.

For example, both Jews and Muslims feel like they have a right to the land of Israel and Palestine because they have ancient cultural attachments to them. But don't worry, those rival attachments to the same land haven't caused any geopolitical problems in the world. No, they've caused a lot. It's a real problem.

Anyway, the second human factor that determines how population is distributed is economics. People tend to settle where they're confident that they can make a living, you know, where resources and jobs are abundant. And that means economics can often be a major reason for migration as well.

For example, those who are The government responsible for the African slave trade had significant economic incentives to move millions of enslaved Africans from their homes in the Americas starting from the 15th century. Also a major factor in the large waves of immigration in the United States during the 19th century was that jobless Europeans were looking for work, and they found it. in America.

So they packed up their bags and they migrated. Okay, now a third human factor for population distribution is history. And what I mean is, how populations were distributed in the past can have a strong influence on how they are distributed in the present. For example, over half of all black Americans live in the South, and that has a lot to do with the history of slavery in America.

Almost half of all Asian Americans live in the West because their ancestors migrated from Asia and settled there. Okay, now a fourth human factor influencing population distribution is politics. So you know, if a group of people don't like the politics in their region, maybe they move elsewhere.

And this was the case for a great deal of the immigrants coming to America from Europe in the 19th century. A lot of them weren't exactly fans of the tyrannical turds running things back home, so they migrated here to America, and you know, that was voluntary. But also people can be forced to move because of political regimes. For example, in 1975, the totalitarian Cambodian regime known as the Khmer Rouge forced millions of Cambodians from their capital city into the rural countryside.

Okay, so those are all of the high-level reasons why the arts population is distributed. But now we need to talk about a related concept, namely population density, which is a measure of how many people occupy a given unit of land. If that sounds like the same thing I was just flapping my mouth hole about in the last section, it's not.

In the last section, I was flapping my mouth hole about population distribution, which asks where do people live. Here we are talking about We're talking about population density, which asks how many people live here. So don't get confused with the two, I know you want to!

But don't. So when it comes to calculating population density, you need to know the three methods geographers use, and you need to understand the value of different calculations for answering questions about the pressure those populations exert on their land. The first kind of calculation is called arithmetic density, which is the total population divided by the total land area.

And that's all the land, even the land that's uninhabitable. Because this measure of density includes every square inch of land, the result doesn't necessarily tell the whole story. For example, Taiwan has one of the highest population densities in the world, but three quarters of its people live on one.

third of its land area. So arithmetic density does not account for this, and that number might lead you to assume that the population is distributed evenly across Taiwan, which they are not. Okay, now a second kind of calculation is physiological density, which is the total population divided by the total amount of arable land. Waterable land? Arable land.

It means land that can be used for agriculture. So this is a measure that demonstrates whether a population is able to feed itself. Like, is there enough arable land to grow enough crops to feed everyone's mouth hole? And the higher the physiological density, the more pressure will be put on farmland to produce enough food, and the lower the number, the less pressure on the farmland.

For example, the United Arab Emirates has about 32,000 square miles of land and almost 10 million people as of 2020. But only about half a percent of that land can grow food, because you know, it's in a giant stinking desert. So this is a good good example for us to compare the different insights generated by different calculations of population density. So the arithmetic density of the UAB gives us 312 people per square mile.

And hey, that doesn't sound so bad, does it? But when we consider how much farmland is available to feed all those people, which is to say we calculate the physiological density, we get over 6,000 people per square mile. That's a lot of density, Tony. Okay, now the third method of calculation you need to know is agricultural density, which is the total farmers in a place divided by the total arable land.

So here, a lower number means less farmers available to grow. grow food. But that doesn't necessarily indicate that everyone in that place is going to starve.

Especially in wealthy, industrialized countries, a lower agricultural density means that farming has become mechanized. So yes, there are fewer farmers, but that's because they can use those big honking machines to do the farming for them. On the other hand, a high agricultural density usually means that many farmers are subsistence farmers which means they grow only what they need to survive and they don't sell it on some distant market. Now it's important to know that none of these calculations tell us the whole story alone, but if we get them in a big equational hug, then we start to get a complete picture of population density and its implications for how people put pressure on their land.

But, okay, who cares? Why does calculating all this even matter? Well, it matters, my young pupil, because population distribution and density can significantly affect four processes that you need to know.

First, density and distribution affect political processes. For example, here in America, a census is taken every ten years, and once they find out where all the people live, seats are gained or lost in the House of Representatives, and that can shift the balance of power in Congress. Second, density and distribution affect economic processes. Population density numbers determine how money is spent for both private and public services. So if an area is growing rapidly in population, businesses have more incentives to open stores and offices in those locations, and the opposite is true in places with decreasing populations.

And governments also allocate money for infrastructure projects like roads and bridges based on whether these places'populations are growing or declining. Third, density and distribution affect social processing. And these calculations can determine how accessible public services like schools or hospitals are to a given population. Like, it's way more cost-effective to build a hospital, for example, in a densely populated area than in a sparse. So you know, if you live out in the country and you wake up with a kidney stone the size of a baseball, well, it's gonna be a long night.

And fourth, density and distribution affect the health of the environment and access to natural resources. You see, as a population grows, more people need to eat and drink, and that means more pressure on the land and water sources. And central to this concern is the question of the Earth's carrying capacity, which refers to the maximum population an environment can support.

And geographers fight about this like children fighting over who gets to dig up all the gyroids after it rains in Animal Crossing. And they debate because so many factors come. complicate the potential carrying capacity, including climate, agricultural productivity, technology, etc. Some studies say that the Earth's carrying capacity is 500 million, while others say it's over a trillion.

But determining carrying capacity is even more complicated when you consider that not all people use the same amount of resources. Middle class Americans, for example, use far more resources than they need to survive, and that decreases the Earth's carrying capacity. Like, if everyone used only what they needed in the carrying capacity, might be easier to determine.

But, you know. They don't. Okay, so we've talked about how population is distributed and how dense it can be and how that- calculate population density and why all that matters.

So now let's turn the corner and talk about population composition, which is the measure of certain characteristics of a population like age, race, gender, etc. There are two very important elements of population composition you need to know. First is the age structure of a population, which is an organization of population based on age groups.

So people like me in my early 40s would be an age group, and then people like my grandpappy who was older than dirt and dog ears is another group. Son, I may be old, but I can still wear you out. Yep. That's true. Anyway, knowing how many people fit into different age groups enables geographers to draw conclusions about whether a population is growing or stable or declining and we'll talk more about that in a minute.

Now, one very important- Part of the age structure that you need to know is a population's dependency ratio. Now dependents are people who, you know, depend on others to survive, usually children under the age of 15 and elderly people over the age of 65. In other words, these are people who are generally not working to support themselves. And knowing this ratio is helpful in figuring out the pressure put on the working age population to support other non-working dependent groups. So think about it this way. Suppose these two parents both work, and together they make $100,000 a year, and they only have one child or you know, one dependent, this would be a low dependency ratio.

And then this family over here makes the same amount, but they have five children, this will be a high dependency ratio $100,000 is going to go a lot further and providing for the needs of that one child than it will for five children. You smell what I'm stepping in? So that becomes a very important measurement for a given population at national, regional, and local scales to determine current and future levels of productivity in the working population. A higher dependency ratio indicates fewer working-age people supporting more dependents, while a lower dependency ratio indicates more working-age people supporting less dependents.

And just for poops and giggles, you should know that the dependency ratio is calculated by taking the number of people in the dependent age group and dividing by the number of people in the working age group, multiplying by a number of people. Okay, now the second element of population composition you need to know is the sex ratio, which represents a comparison of males to females in a population. And depending on the scale we use, the sex ratio can be different. On a global scale, the sex ratio is about 101 men to 100 women.

But zoom into a single continent like Europe and the ratio is 95 to 100. Or zoom in further to just one country and we'll choose China for funsies and the ratio is 110 to 100, and that's a result of their one-child policy, but we'll talk about that later. Here are some key tools geographers use to compare the age structure. and sex ratios is the population pyramid.

And oh- Baby, are you definitely going to see this on your exam. So let's talk about how to interpret it and why it's important. So here on this global pyramid you see five year age increments on the Y axis and male female percentages on the X axis.

So this tells you that out of the world's entire population in the 50 to 54 age range, 2.9% are male and 2.9% are female. Easy peasy lemon squeezy. Now the reason population pyramids are such powerful tools is because depending on the shape of them they can tell us whether a population is growing or declining. Let me show you the four typical shapes that illustrate those trends.

This shape illustrates a population. population in rapid growth. You see that wide base?

That means that there are way more young people than older people. And this shape often occurs in developing countries where the birth rates are high and the lifespan is shorter, like for example in the Democratic Republic of the Congo. So a population in rapid growth will need to focus many of their resources on providing for the needs of children, like, you know, education. Now a population in this shape is still growing, but it's an indication of slow growth.

Here the birth rate is only slightly higher than the death rate. It's still a pyramid, but the base is much narrower. A good example here is China, and the narrow base shows the result of their one-child policy that I mentioned earlier.

Then there's this shape which indicates stable growth. Here the birth and death rates are similar and there's a roughly even distribution throughout the different age ranges. And a good example of stable growth is the United States.

And finally, this shape here is kinda bad news because it indicates population decline. Here the death rate is higher than the birth rate and that's why the base is narrower than the top. Germany is a good example here, and for populations in this kind of shape, they're gonna face challenges like labor shortages and decreasing demand for consumer products.

products. Okay, be honest, have I told you more about population than you ever wanted to know? Yep. Well, don't worry because there's more. So now we need to talk about population dynamics, which is all about how geographers study the trends in population growth or decline.

And for that they consider three areas, fertility rates, mortality rates, and migration. Now the fertility rate is the measure of a population's ability to have children, and that is important because, to paraphrase the notorious B.I.G., that great philosopher of population phenomena, Mo'Baby's Mo problems. And to be fair, you know, less babies, less problems, but it's not as catchy.

Anyway, knowing the fertility rate is useful for governments, for example, who want to know whether their populations are growing or remaining stable or declining. With this information, they are better able to plan and allocate funds for infrastructure projects and education and healthcare. And I know what you're thinking, but Heimler, how do you measure the fertility rate?

I got you. First is the crude birth rate, which is the number of births per thousand people in a given year. So a simplistic example would be this. If you have a population of a million people and 10,000 babies are born, then both get divided by a thousand and you can get a crude birth rate of 10 per thousand. This measure is useful for predicting future population growth.

So for example, the lowest crude birth rate in the world is 10. The highest crude birth rate in the world right now is Europe, and the highest is in Africa. Now, a potentially more accurate measure of a population's growth or decline is its total fertility rate, which indicates the average number of children one woman will have during her childbearing years, which is roughly age 15 to 49. Now this measure of fertility is more accurate than crude birth rate because it only considers the part of the population who are capable of bearing children. Additionally, a country's total fertility rate is often a signal of that country's access to healthcare and medical services. What I mean is, a lower total fertility rate tends to occur in wealthier countries where access to healthcare is more important than the total fertility rate.

healthcare and family planning services are abundant. In those places, it's easier to avoid unwanted pregnancies. And the opposite is true for less developed countries with higher total fertility rates.

Now you should know that a TFR of 2.1 is the rate at which a population will remain stable because last time I checked it takes two people to have a baby and so they need to have at least two babies to replace themselves in the population. So Europe's TFR as of 2020 was about 1.5, which means they're experiencing population decline, whereas Africa's was 4.3, which means population growth. Okay, so that's fertility rate.

Now, the second measure geographers consider when studying population growth and decline is mortality rates, which indicates a population's rate of And here there are two varieties of measurements to know. First is the crude death rate which measures the number of deaths per thousand people. Now at a global scale the crude death rate is currently about 8 per thousand. But in 1960 it was 13 per thousand and it has steadily declined since then.

So that means that worldwide people are living longer on average. And that's great because that means I'll be around much longer to hurl sassy AP videos onto the internet for you marvelous people. Now the question is, why are people living longer today than they have in the past?

Well, in general, people are experiencing longer lifespans because of better nutrition, better quality medical care, and expanded access to clean water. So put all those factors in the pot and baby, you've got a stew that smells like an increased life expectancy, which is how long an average person is expected to live. And again, scale matters. Like in some wealthy developed nations, the life expectancy is 80 years, while in many developing nations it's more like 50 years.

Okay, another related measure of population growth and decline is infant mortality rate, which is the number of children who die before they reach the age of one per 1,000 live births. I said before that a low crude death rate can be explained by better access to health care, but the infant mortality rate is often a better indicator of a country's access to health care than the CDR is. In places with a high infant mortality rate, they tend to have less access to life-saving interventions and medicines to help babies survive infancy. And in places with a low infant mortality rate, they tend to have more access to health care.

Okay, so those are the kinds of measures you need to know, so let's start putting them together. Geographers use both the crude birth rate and the crude death rate together when they want to study change. changes in populations.

So take the CBR and subtract the CDR and that gives you the rate of natural increase for a population. So if a population has a crude birth rate of 20 births per thousand and a crude death rate of 10 deaths per thousand, then the rate of natural increase will be 10, which, you know, is 20 minus 10. In this case, the rate of natural increase is positive, so the population is growing. But if the RNA is negative, then the population is declining.

Now, to be clear, this measurement of growth or decline is only about a population's births and deaths. deaths, but those aren't the only ways a population changes. Anyone know any other ways that populations can grow or decline? Anyone? Anyone?

Oh, me? Ah, migration? That's right. So the RNI says precisely nothing about population increase or decline due to migration, and we'll get to that in a minute. But for now, just understand that even if a country's RNI is steady or declining, they might still see an increase in population due to migration.

Now another reality geographer study with reference to population is the doubling time of populations, which is exactly what it sounds like. Given the current population growth trends, how long will it take for that given population to double? And this number varies according to the crude birthing, death rates, infant mortality rates, and the rest.

So, Ethiopia's doubling time will take 20 years. 27 years. Why?

Because it's in the rapid growth phase and it won't take long to double that population. But the United States will take 233 years to double because it's in the stable growth phase. Okay, now that we've talked about the fact of growing and declining populations, now we have to consider the various factors that influence fertility, mortality, and migration.

And the first influences are social and cultural factors. For example, different cultures have different expectations for women, which can play a significant role in fertility rates. Some cultures have strict gender roles and expect women to stay home, raise large families, and make their husbands sandwiches, which can lead to a higher fertility But in other cultures, women have more freedom to pursue education and careers, which can often lead to fewer births, leading to a lower fertility rate. And second, political factors influence fertility, mortality, and migration. Governments monitor their population growth carefully and can encourage or discourage births.

And we already talked about one example of this, namely China's one-child policy enacted in the 1970s. During that time, the Chinese government was getting all sweaty as they looked at the explosive growth of their population, because, you know, Too many mouth holes, not enough food to feed them. So they enacted the one child policy to restrict their population. On the other hand, when governments see that their population is declining, they can encourage families to have more babies by passing laws guaranteeing access to health care, more generous maternity or paternity leave from work.

But third, there are also economic factors that influence fertility, mortality, and migration rates as well. Birth rates often decline during economic downturns when people are worried that they don't have enough means to care for more children. But when the economy is good, people will be making babies because they're optimistic about the future.

So So look, here you see that during the Great Depression here in the United States, the total fertility rate in the U.S. was a real low. Like, nobody had any money, so fewer babies were born. But look, here's the baby boom, which coincided with a wave of incredible economic prosperity, and then the economy started tanking again about here and, you know. You get it. But economic factors can also determine rates of migration.

For example, during the 19th century the United States economy was in general doing very well while Eastern and Southern Europe's economies were, to use the technical geographical term, a turd halfway to being flushed. And that economic reality led to massive migration to the United States of European immigrants looking for work. Okay, now everything we've been talking about thus far is all about measurements and percentages and precise mathy mathy stuff.

But I can see it in your eyes. You want to get a little more theoretical about population dynamics. And that's great because that's exactly what we're about to do, y'all.

And I want to explain. explain to you two theoretical models that attempt to explain population growth. First is the demographic transition model, which is a graph that attempts to explain the growth and changes in human population. population over the course of history by considering birth and death rates.

But before I explain what all this means, you need to remember that this model was created to explain European and American populations, and that means it might not be as useful for explaining population realities in other areas of the world. Now, you will absolutely see this on your exam, and it looks all kinds of confusing, but just stick with me and I will help you understand. So the basic function of this model is to chart how crude birth rate, crude death rate and the rate of natural increase change as the society passes through these different phases of history. So stage one is called the high stationary phase and a population in this phase is pre-industrial and agrarian. Now agrarian means that these people are mainly farmers and pre-industrial means that everything they needed to live like you know clothes and tools were made by hand and not machines.

So in this phase you can see that the birth rate and the death rates are both high which means that they kind of cancel each other out. Like a lot of people are being born and a lot of people are dying and so everything is basically even. And that leads to a stable population that basically remains steady or growing a little or shrinking a little. Now, agrarian people tended to have a lots of babies because they needed help on the farm. Well, son, you're four years old now and That goat ain't gonna milk itself.

But all those babies are not going to lead to significant population growth in this stage because poor nutrition and disease meant the average lifespan was somewhere in the 30s, making the death rate high as well. And as the world currently stands, no present nation is in stage one. But then we get here to stage two.

which is known as the early expanding stage, which corresponds to a population's entry into industrialization. Now we're going to talk all about industrialization in Unit 7, but for now you just need to understand that the Industrial Revolution marked a transition from an agrarian society to a modern mechanized society. So here the birth rate remains high, but the death rate begins to drop precipitously due to advances in science and new medicines and better nutrition, vaccinations, etc. So that led to a dramatic increase in lifespan.

People are living longer. That's still a lot of babies are being born, and so this gap right here indicates a population explosion. And then we move right along to stage 3, which is the late expanding stage. In this stage, populations are continuing to industrialize, medicines are getting better, more people have access to nutritious foods, education becomes more important, etc. And under these conditions, the birth rate begins to decrease sharply.

And the reason is that as more people have access to education and get further away from life on the farm, children are not necessarily an asset for work. But even so, there are still more births than deaths, so in this stage, the population grows slowly. many developing nations are in this stage.

And then moving along to stage 4, we have the low stationary stage. And at this stage, a country is considered to be completely industrialized. And here you can see that birth and death rates are similar, which leads to a slow population growth or stabilization. And when a population arrives in this stage, it has new worries about an aging population and all the issues that come with it.

And today, most developed nations are in this stage. Now when this model was first introduced, it only had four stages. But recently a potential fifth stage has been added.

Geographic intrigue? This stage is called the natural decrease stage. So in every stage before this, populations were either stable or growing. But here we get the ultimate wah-wah as the death rate exceeds the birth rate and the rate of natural increase begins to decline. Now some European countries along with Japan are now in this stage.

But remember, the populations of these countries might still grow through migration, so, you know, Fingers crossed. So again, this is a theoretical model that traces how populations grow and decline through specific periods of historical development. And the key theme of this model is a country's level of industrialization.

But there's another model you need to know that looks at population growth and decline not through the lens of industrialization, but instead through the lens of disease. It's called the Epidemiological Transition Model, and this model focuses on the death rate and tries to explain why the death rate changes over time. Now, in case you don't know, epidemiology is the study of how diseases spread. So, maybe think of this model as the nasty germ transition model.

Anyway, in this model, stage 1 is known as famine. In this stage, people can die from dang near anything. Infectious or parasitic diseases, bear attacks, whatever. If it's lethal, you can die from it in this stage. And probably the most dramatic example of populations in this stage is the spread of the bubonic plague, otherwise known by its cuter, more playful name, In the 13th and 14th centuries, this disease spread along trade routes throughout Afro-Eurasia and killed a fourth to a half of any given population.

Therefore in the famine stage, the death rate is high and life expectancy is low. The population can grow, but usually it grows in bursts and is not sustained over time. Stage 2 is known as the receding pandemic phase, and here life expectancy increases significantly from about 30 to about 50 years old and the death rate begins to decline. Populations enter this phase when they begin to have access to improved sanitation and nutrition and medicine, all of which helps fend off the great plagues killing humanity.

But don't celebrate yet because people are still dying by the metric b- buttload in this phase, and here people are mainly dying from pandemics, which are diseases that are spread throughout regions in the world. And this is especially true because people in this stage often are living much closer together in cities, which is where the nasty germs can spread real easily. And then we move right along to stage 3, which is known as the degenerative and human-created diseases phase. Now here the death rate is still low and life expectancy continues to increase. Now you'd think that'd be a good thing for people to be living longer, like puppies and rainbows as far as the eye can see.

But longer life brings other problems with it, especially diseases associated with old age, like heart disease and cancer. Okay, now stage four is called the delayed degenerative disease phase. And this is the stage where life expectancy is at its highest.

Here, medical technology advances significantly to address diseases that are so common that it's hard to even imagine what they would be. associated with aging. So you know for heart disease we get bypass surgery and for cancer we get chemotherapy etc.

And dang it, I wish I could tell you that's where we're all headed. Better and better medical technology and longer and longer life span. But this model is here to crush any hope you have because we also have stage 5 known as the re-emergence of infectious disease phase. Yeah, it's great that we developed all those medical technologies to fight off diseases, but here infectious and parasitic diseases develop immunity to our drugs and our antibiotics and then they come right back. Therefore those diseases become a deadly threat yet again and life expectancy Okay, now the main critique of the epidemiological transition model is that it oversimplifies the causes of population change due to diseases.

In other words, this model doesn't account for differing historical periods or locations. Additionally, the ETM doesn't account for poverty as a cause of the spread of disease, which is a major omission. Poverty is one of the most significant causes of shortened lifespans and probably does a better job explaining differences in death rates and the spread of disease.

So there you go, if you're at a party and you get into an argument about the efficacy of the ETM to explain population patterns, well now you're well equipped to hold your own. Or maybe that's just the parties I go to. Anyway, moving on. Okay, now let me introduce you to yet a third theory on population growth and decline, namely the Malthusian theory. Now Thomas Malthus was a cheery British demographer who lived in the 18th century and looked around at the European population trends and was like, yep, everybody's gonna die.

He was a fun guy. Anyway, his worries were centered on the dramatic increase in the population that he was observing, which was happening for two reasons. Birth rates were slowly increasing, but thanks to advances in medicine, the death rate decreased sharply.

So not only were there way more infants surviving childhood, but people were now living healthier and longer lives. So you and I look at those developments and we're all like, thumbs up! But not Thomas Malthus. He looked around at people living longer and not dying from disease and was like, Oh, this is terrible.

Anyway, the reason these developments worried Malthus is because he observed that while the population of Europe was growing exponentially, the food supply was only growing arithmetically. And I know that doesn't make any sense to you, let me say it differently. He worried that if the population kept expanding as rapidly as it was, then by 1800 there would be more people than food to feed them, which would result in massive famines and plagues, which would be the only way to decrease the population. So Malthus summoned his inner Thanos and argued that people should delay marriage and have less children so that everyone wouldn't die.

Now, spoiler alert, Malthus was wrong. From our vantage point a couple centuries later, we can see what Malthus could not, namely that new technologies like mechanized farming and chemical fertilizers enabled the growth of the food supply to keep up with the population. So sorry Thomas Malthus, you're basic. Okay, now let's leave all the theoretical stuff behind and talk about consequences of population growth or decline.

Like why does all this matter and to whom does it matter? Well first, population data matters too. In some cases, governments can attempt to influence the population growth, you know, the rate of natural increase of their populations, and they can do that in several ways.

First, they can introduce antinatalist policies, which are policies intended to decrease the number of children born. And usually this is done because governments are concerned that their populations are growing too fast for their resources to keep up. I'm looking at you, Malthus.

And the most famous antinatalist policy was, once again, China's one-child policy. Now on the other side of the spectrum, governments can introduce pronatalist policies, which are policies intended to increase the number of children born. increase the number of babies born.

And usually governments do this because they're worried about the effects of an aging population. More specifically, as the population ages and stops working, there may be a gap in working-age people to fill necessary jobs to keep the economy afloat. And that is a No bueno. So pro-natalist policies can include generous parental leave from work and free day care and other means to decrease the expense of raising children. And then third, don't forget that populations can grow or decrease because of migration, and so governments can also introduce immigration policies which either allow more immigrants in or restrict the flow of immigrants.

For example, in the 1950s and 1960s, as Western Europe was recovering from World War II, they experienced an economic boom. However, because of the significantly decreased population due to the staggering amount of immigrants, the population grew. deaths in the war, several nations passed policies basically inviting immigrants to come live and work there. Okay, let's talk about the ladies. Now over the last few decades, geographers have focused more and more on women and their role in the world, especially their role with respect to fertility rates.

And what's been most interesting to notice is that as women's status is elevated and they have more access to healthcare and contraception and education, fertility rates tend to decrease. On the flip side, in places that uphold more traditional gender roles, which is to say women are mainly seen as the bearers of children, those women tend to have more babies. But you need to know that there are basically three ways that women's roles can be elevated in a population. And when women are elevated, it has a significant impact on the fertility rate. First, access to education.

Pretty universally, when women have access to more education, they tend to have fewer children. And to help you remember that, demographers call this the more books, less babies principle. And that happens for several reasons. One reason is that educated women tend to be more skeptical about cultural norms that dictate how many babies they should have.

Okay, now the second way women's roles are elevated is by access to family planning, which include medical technologies that can help women have more control over when and if they get pregnant, and therefore that lowers the fertility rate. And here you have medical technologies like the birth control pill or intrauterine devices. And then the third way women's roles are elevated is by increased access to employment.

As more opportunities for women have opened in the workplace, especially over the course of the 20th century, century, many women delay marriage and childbearing in order to focus on their careers. Now it's also important to know that the changing roles of women ...also affect mortality and migration, and first let's consider mortality. Now, as I mentioned, as women have more access to education, health care, and family planning, they do have fewer babies.

But the fewer babies they do have are more likely to live. In other words, as women are elevated, the infant mortality rate decreases. let's consider the effect of women's roles on migration.

And here let me introduce you to my boy Ernst Georg Ravenstein. He was a 19th century geographer who developed 11 laws of migration to explain how and why and under what conditions people migrate. Now you don't need to know all these laws, but law six says that women are not allowed to migrate.

women are more likely to migrate within their home country, while men are more likely to migrate to other countries. So in countries where women have more autonomy, they are often the chief movers when it comes to migration, and mostly it's rural to urban migration. Okay, so now let's focus a little more on the issue I mentioned earlier, namely the causes and consequences of an aging population. First of all, what in the fresh heck is an aging population?

Well, basically it's a population in which the dependency ratio is increasing, and they tend to have a lower total fertility rate also, somewhere below 2.1. So in terms of a population pyramid, aging populations look like this. look like this.

The middle cohorts are larger than the lower cohorts. So basically an aging population is determined by the birth rate, the death rate, and longer life expectancy. So those are the causes of an aging population, and now what are the consequences?

And I can think of three. First, you have political consequences. As the population gets older, they can have a significant effect on the balance of political power in a country.

For example, in the United States, the most reliable voters are those over the age of 65. So while the 18 to 25 year olds are busy trying to become ticked off, they're also trying to TikTok influencers, those retirees are in the voting booth making sure their interests are protected. And that means that in general, as a population ages, the policies passed by Congress will reflect the interests of senior citizens, the most significant of which is social security and healthcare. But second, there are also social consequences of an aging population, like for example providing care for the elderly. You see, the more a country industrializes, the more likely a society is defined by the nuclear family instead of multi-generational households. And as you may know, nuclear families move all over the dang place, away from the older generations.

lived close, then the younger members of the family could care for the older members of the family when that time comes. But in the age of the nuclear family and increased migration, more elderly people are moving into retirement and nursing facilities to get the care that they need. A third, there are economic consequences to an aging population. So as a population ages, they pay less in taxes, and if a population is made up of a majority of older folks, then that presents a big, fat economic problem. For example, here in the US we have Social Security, which provides monthly payments to retired people.

And do you know who pays for the current generation of retired people? people of working age. So look, you can see the problem.

There are a lot more people retiring than there are working, and that is a major economic... problem created by an aging population. In fact, the prediction is that the Social Security Fund will be depleted by 2031, so by the time I retire, all that money I've been putting into that fund since I was 16 years old will be gone, and I'll go have to live in a van down by the river. Okay, enough of that. Now let's get to our last major section, which is all about migration, and I reckon we ought to start by talking about why people migrate.

But first, let me clear something up so you don't get confused. You're going to hear me use two words that kind of sound the same, but they are not. Immigration and emigration. Immigration refers to people coming into a country, while emigration refers to people leaving a country.

Immigration in, emigration out. We good? Now, why do people migrate?

Well they migrate because they experience either push or pull factors. Push factors are negative experiences that push people out of their country. So maybe a war or persecution pushes refugees out of their country to find shelter in another country.

Or maybe it's famine or a natural disaster like Hurricane Katrina in 2005, which sent around a million Louisiana residents seeking shelter in other states. On the other side, people migrate because of pull factors, which are positive factors that attract migrants to a new place. Maybe- pulling them out of their home. So for example, pull factors can include new job opportunities or seeking freedom under another country's more stable government.

And hopefully it's obvious, but when people decide to migrate, they're usually experiencing a combination of push and pull factors, like they rarely occur in isolation. So for example, during the Irish potato famine in the 19th century, millions of Irish poor were starving. So you know, that's a push factor.

So as a result, many of them migrated to the United States because there was food and work over there. That's a pull factor. All right, you mowing what I'm growing?

Good. Okay, so people migrate because they experience significant push and pull factors. But when they make the decision to leave for their new destination, they will almost always experience intervening obstacles and opportunities. Intervening obstacles refer to challenges that they must overcome in reaching their desired destination.

On the other hand, sometimes migrants experience intervening oppor- opportunities, which can be anything that they encounter that changes the original destination of their migration. Now to further complicate things, all of these push and pull factors and intervening phenomena can be categorized under five headings. You've got cultural, demographic, economic, environmental, and political. And let me explain each of these with some examples very quickly. In the cultural category, persecution can be a push factor, as it was during the partition of India.

After World War II, the northern part of India, which was a Hindu majority, was sectioned off to create Pakistan, which would be a Muslim majority nation. So Muslims who no longer felt welcome or safe in India, India migrated north to Pakistan while Hindus migrated south to India. And that became a horrible mess and the loss of life during that event was staggering. Now in the demographic category, rural people may migrate because they lack access to healthcare services. Or urban people may migrate away from the city because of the dense population there and there are just not enough jobs for everybody in that city.

And then in the economic category, people tend to migrate to find jobs to support themselves and their families. A good example here was the Bracero program, which was an agreement between the Mexican and US government during World War II. And because the US was busy moping, Globalizing to blow people up in distant lands, agricultural and transportation jobs were going unfilled. And as a result, over 4 million Mexican workers migrated across the border to fill those vital roles.

Now in the environmental category, in addition to natural disaster displacement, people may migrate because the climate of a region is more desirable than their current climate. For example, Florida is home to the largest population of retirees in America, many of whom migrated to avoid the butt-cold winters of the American North. Then in the political category, war is a major political push factor that sends many migrants seeking safer conditions elsewhere.

For example, the Syrian Civil War, which began in 2011, 11 has been responsible for the emigration of more than 5 million Syrians from their homeland. Okay, now there are two major categories of migration that you need to know. There's forced migration and voluntary migration, and each of those are exactly what they sound like.

Forced migration occurs when people leave their homes against their will. Probably the example you are already familiar with is slavery. But slavery isn't the only kind of forced migration. As I mentioned before, people often flee their country because of war or persecution. For example, hundreds of thousands of Armenians fled their homes during the Armenian Genocide in the first part of the 20th century.

So people flee their homes because of war. who migrate for these reasons are known as refugees, and refugees have the right under international law to seek asylum or protection in other countries. But there's another group of migrants known as internally displaced persons who leave their homes for similar reasons, but they just go to another part of their own country. So forced migration is always ugly and creates all sorts of human crises. But let's brighten things up a bit and talk about voluntary migration, which occurs when people leave their homes because they want to.

And because one, geographers love to categorize things and two, they hate you. There are seven categories. There are two categories of voluntary migration you need to know.

The first category of voluntary migration is transnational. These migrants, while they live in the place that is not their home, retain strong ties to their culture and their family back home. It's like they live in two cultures at once across national boundaries. So one major way this often works out is this. If the migration occurred to find work, then the transnational workers will often send money home to the people they left behind, maintaining that relational connection across distance.

The second category of voluntary migration is called transhumans. This refers to migration by people who move not because of unfa- foreseen push and pull factors, but because movement is their way of life. And although there are fewer and fewer of these groups of people today, nomadic peoples who move from one area to another would fit this category.

Now, the third category of voluntary migration is called internal migration, which refers to people who migrate within the borders of a country. Now, according to Ravenstein's laws of migration, most migrations occur over shorter distances because, you know, there are less intervening obstacles encountered over short distances. Makes sense.

Stay with me now. The fourth category of voluntary migration is called chain migration. The idea here is that one group of migrants can often cause other migrants to follow them.

So the first stage of chain migration might be a group of migrants who settle elsewhere because of various push and pull factors. And then once they've established themselves in that new location, they stay in contact with those they've left behind. Then after some time passes, if they have found a better life in their new destination country, the people they left behind will often migrate and settle with them in the same place. So back to the huge Irish immigration to America that we talked about earlier, this is is a good example of chain migration. The first wave of immigrants was pushed out of Ireland by famine, and even though they were no longer starving in America, they did face a pretty rough reception.

But over time, as Irish immigrants became more and more part of American society, more Irish people immigrated and found their new home much more accommodating. Okay, the fifth category of voluntary migration is called step migration. The idea here is that a migrant's journey often occurs in stages, or steps, and not all at once. So a group of migrants may plan to arrive at this destination here, but then they encounter intervening obstacles or opportunities as they often do.

As a result, they may choose to settle in villages and cities along the way until they can make the next step and leave for their ultimate destination. The sixth category of voluntary migration involves people called guest workers. This is a temporary form of migration in which migrants travel to a new country to work for a specified amount of time.

I already mentioned the Bracero program earlier, which is a good example of that. And then finally, the seventh category of voluntary migration is known as rural to urban. Now this is the movement of people from sparsely populated countryside to densely populated urban centers.

And this particular kind of migration has been increasing ever since the rise of the Industrial Revolution. Alright, well give yourself a good slap in the face to wake up and let's push through this final section to talk about the effects of migration. Those effects fall into three categories, political, economic, and cultural.

First, migration can have significant political effects. For example, when people migrate can change the distribution of political power as it did here in the United States in the mid 20th century when a bunch of people from the North and Midwest migrated to the Sunbelt states. But immigration can also have negative political effects. So when immigrants arrive in large numbers, it can sometimes make the native-born people who live there a little cranky, and as a result the government may pass laws restricting immigration. Probably the most notorious example of this in American history was the Chinese Exclusion Act of 1882. You see, in the 19th century, Chinese immigrants to America surged as jobs in the railroad industry opened up.

But native-born Americans began blaming the Chinese immigrants for keeping wages low and taking their jobs. So the Chinese immigrants were forced to leave the country. And I'm pretty sure the only reason we got those jobs to begin with is because you guys didn't want it. Regardless, the result was that Congress passed the Chinese Exclusion Act, which enacted a 10-year ban on Chinese immigrants.

So yeah, I'd say that had a negative effect on immigration. Second, migration can have significant economic effects, and these can be felt both in the destination countries where these migrants are going and in their countries of origin, you know, where they are leaving. The migrants'destination countries benefit from immigration because immigrants often come seeking work. Additionally, immigrants will often accept jobs at lower wages in sectors where native-born people are less- willing to work.

Today, two of the biggest of those sectors are agriculture and construction. This arrangement can be extremely helpful to a country with an aging population because more workers in the economy decreases the dependency ratio. Oh man, we're just tying all these concepts together. Feels good, doesn't it? But the migrants'countries of origin also feel the economic effects.

With working age people leaving, more jobs are open for those who remain behind. Additionally, immigrants often send money back to their country of origin, and the term for that money is remittances. And as far as the role of remittances in the world economy, they're no joke.

According to the World Bank, in 2022, over $630 billion in remittances circulated between immigrants and their families and friends back home. But flip that same coin over to the negative side, and we see that since the majority of migrants who leave a country are of working age, then that can create a problem. problem if there aren't enough people to fill the jobs that they left behind. That can create slow growth for the country of origin's economy. And third, there are cultural effects of migration.

In destination countries, a significant cultural effect is the introduction of the immigrant's culture, their language, their religion, their music, etc. For example, as a result of the large influx of Mexican immigrants to America since the Bracero program, Mexican food is a staple item in the United States. And I have to be honest, I ain't mad about it. Now in countries of origin, the cultural effects of migration are often connected to economic benefits.

Because of the prevalence of remittances, families left behind in the country of origin can often afford a better lifestyle than they otherwise could. But on the negative side, the social structures in the countries of origin can be strained by migration. Families can be broken apart when one of the parents, usually the father, departs looking for work elsewhere, and that's rough on the family. In this case, the dependency ratio increased, putting more stress on the working population there. Okay, now to keep reviewing for Unit 2, click right here and keep watching.

Click here to grab my AP Hug Heimler Review Guide, which has everything you need to get an A in your class and a 5 on your exam in May. I'll catch you on the flip-flop. Heimler out.

Transcript for:Overview of AP Human Geography Unit 2

Transcript for:
Overview of AP Human Geography Unit 2