hello there geographers and boy oh boy do I have a good one for you today in this video we are going to review the rank size rule primate cities the gravity model and the central place theory as we seek to better understand the distribution of different settlements and the patterns that they form oh you can just feel the excitement of learning in the air now to start let's talk about how the size of a settlement impacts how we classify different cities generally we can see countries follow either the rank size rule or the primate City rule countries that follow the primate City rule traditionally have one large city the city often has at least twice the population of the second largest settlement in the country primate city has significant political economic and social control over the rest of the country with most of the opportunities in the country being located in the city this leads to Residents in a primate City to have access to a variety of different goods and services something that is not true for residents in other settlements around the country this concentration of goods and services causes people living in other parts of the country to have to travel farther for what they need since they are traditionally only located in the primate city so we can see that countries with a primate City often have unequal Economic Development which can cause countries to experience devolutionary pressures as Citizens may become frustrated with the unequal development plus it also increases the risk of future problems since the country is now dependent on the success of one city instead of being able to rely on multiple settlements for example if anything were to happen to the economy of the primate City it would most likely result in hardship for the entire country since the majority of economic development is focused in that one area today we can look at Mexico City as an example of a primate Sid notice that the population of Mexico City is significantly larger than the rest of the top cities in Mexico one other example of a country with a primate City would be South Korea if we compare the different cities in South Korea we can see that Seoul has a significant larger population compared to the rest of the city's in the country now some countries don't have a primate City and instead follow the rank size rule this happens when the second largest city in a country has about half the population of the largest city with the third largest city having a third of the population as the largest city the fourth city being a fourth as large as the largest city and so on so we can see if a country follows the rank size rule we will take the population of the largest city and divide it by two to get the population of the second largest city three to get the population of the third largest city and by four to get the fourth largest city countries like the United States Canada and Brazil would all be examples of countries that follow the rank size rule unlike countries with the primate City there is not just one city that has the majority of economic and social opportunities this reduces the amount of time it takes for citizens of a country to get the different goods and services that they need and also decreases the dependency a country has on one city since more of their economic potential is shared between different cities instead of being concentrated in just one now since we are talking about the size of different cities we should also quickly review the gravity model a concept we last talked about in our unit 2 topic 8 video when talking about migration this model looks at the distance between different places and the population size of each plate we can see that the larger the settlement is the more pull factors it has resulting in more people migrating to the settlement and more places interacting with while settlements with smaller populations have less pull factors which results in less people migrating to the settlement and less places interacting with all of which makes sense larger cities have more nightlife entertainment and a larger variety of jobs more social opportunities and have a larger variety of goods and services compared to smaller settlements which lack many of those offerings due to the size of their population if you need help remembering the gravity model just think about the gravity of a planet the larger the planet is the larger the mass and the larger the pull towards the planet the smaller the planet the smaller the mass and the less gravitational pull towards the planet so now that we understand the gravity model let's change gears and look at crystaller's Central place theory which is a theory that seeks to explain the distribution and pattern of different cities and towns based on their size when looking at the central place theory we can see a variety of different hexagons which allows us to better understand the spatial distribution of different settlements now in order to help you understand the model let's first break down one of the hexagons so you can have a better understanding of what is happening in the model each hexagon represents an area that is served by a central point traditionally a settlement or business the central place there uses hexagons because they do not overlap and when they are linked together they cover all areas originally the model used circles however the problem with circles was that when put near each other they would not cover all of the land this is problematic because it would mean that there are areas which are not served by any service which is not the case in the real world now in order to fully understand the model you also have to be familiar with the concept of threshold and range threshold is the minimum number of people that are required to support any good or service while range on the other hand is the maximum distance that a person is willing to travel for a certain good or service traditionally the more unique important or specialize the gooder Services the larger the range will be whereas goods and services that are more common easy for others to replicate or more General tend to have a smaller range make sure you're understanding these Concepts let's look at how we could apply them to the world today here you can see we have a hexagon showing the market area for a Subway remember the distance from the Subway store to the edge of the hexagon is the range any people located inside this hexagon would go to this store location for Subway if a person was located outside of this region they would end up going to a different store location now let's say that this store location needs to have a minimum of a hundred customers a day in order to remain open this would be an example of a threshold now unfortunately for our Subway store we can see that there are not a hundred people living inside our market area it so this store would most likely go out of business if it tried to open in this location to see this concept play out in the real world we can look at a map showing the different locations of subways in Dallas Texas we can see that there are quite a few Subways located in the city in fact maybe you yourself have actually noticed that there are actually quite a few Subways located in your own city as well this is because Subway knows it is a restaurant of convenience and they know that their range is small their goal is to make it easy to get to their store but the question is why are some Subways more dispersed while other Subways are clustered together well we can see that this is most often due to the amount of time it takes to get to each store Subways that are located in densely populated areas with busy streets and traffic will be clustered together Subway knows that their range does not extend as far in terms of miles in busy urban areas so they will sometimes put a Subway store just right across the street from another store that's because these stores end up serving two different Market areas and do not actually compete with one another even though it may seem like they do while Subways that are in areas with less traffic and a lower population density can be more spaced out since people can easily travel between the locations we're thinking about this just think about what you would do in your own life for example if you were hungry and you wanted to go get Chipotle which of the following Chipotle locations would you go to if I had to guess on which location you picked I would bet that you picked Chipotle number two not because it's the closest one but because it took the least amount of time to get there just like subway Chipotle's range is smaller and will only take so much time out of our day to go to so that is an example of a business with a small range but what about one with a larger range we can look at a Specialized Service such as a professional football team where we can see that one Stadium can often serve an entire State this service has a large range and will pull people from all over a region just one of the reasons why it is rare to have multiple stadiums close to one another another reason actually for fewer stadiums in an area is because of the high threshold that each stadium has which leads to professional stadiums to be low located in major cities with specific site factors and situation facts that allow them to access different Transportation hubs making it easy from people all over the region to get to the stadium okay so now we have an understanding of how this model works with different businesses and understand the concept of threshold and range let's now go back to the model and look at how it works with the location of different settlements right away we can see this model is showing an urban hierarchy the model has a city at the top of the urban hierarchy with towns Market towns and Villages below notice that there is only one city serving the surrounding settlements this highlights the range of the city if we were to change our scale and look at the other areas around this Market we would notice that there are other cities that are serving those areas we can see that depending on the size of a settlement we have different goods and services being offered which impacts their pull and push facts the smaller the settlement the fewer amenities and opportunities that they have it is in that smaller settlement such as Villages wouldn't like to have a larger variety of goods and services they they just simply can't support those businesses unfortunately there just isn't enough people to meet those businesses threshold this is why you don't see hospitals targets or even sometimes gas stations in smaller settlements if they did try to locate there they would end up going out of business this is important to remember when looking at the central place there smaller settlements might not be able to afford or support different goods or services but the people who live in those settlements still need access to them which means that they're going to depend on other settlements for those Services we can see this in the central place theory when looking at the distribution of different settlements notice that Villages which are the smallest of the settlements typically surround larger settlements this allows the villages to have access to different goods and services that their residents need the city will often have the largest variety of specialized services and have the most unique good while the other towns and Market towns will have more General services and goods that people use on a daily basis we can see that the spatial layout of different cities often depends on the size of the settlement which not only impacts the services that they end up offering but also the location of the different settlements the larger the settlement the farther away it can be from another major urban area since they're more likely to have their own Services while on the other hand the smaller the settlement the closer it will have to be to a major urban area or a larger settlement since they'll need to depend on other settlements for their goods and services in real life we can see this play out across countries around the world we can use the central place here to better understand urbanization and the spatial layout of different settlements in the American South which we can see by looking at Kenneth wires study on the central place theory and Southern urbanization the study looked at the south from 1880 to 1930 and found evidence which showed a relationship between small City growth and large city growth which suggested a central place system his research used the central place theory as a tool to better understand the urban development of the region when looking at the American South we can see four clearly dominant Urban centers which together with New Orleans served almost the entire South notice that these cities are fairly evenly spaced out if we actually focus on one city we can see even further connections with the central place there when looking at the city of Atlanta Kenneth Weir noted the resemblance between the Atlanta Urban Network and Chris Dollar Central place theory model Atlanta serves as the main market area serving the surrounding settlements with larger settlements such as Columbus and Athens serving smaller settlements located around them so by understanding both the gravity model and the central place theory we can better understand not only how different settlements impact one another but gain insight into the spatial layout and distribution of different settlements all right now comes the time to practice what we have learned remember if you found value in this topic review video consider subscribing and check out my ultimate review packet for more help with your AP human geography class the packet has exclusive videos practice problems quizzes tests and a bunch more to help you get an A in your class and a five on that National exam as always I'm Mr sin and I will see you next time online