all right it's time to talk about the seven Urban models which describe the internal structure of cities Burgess hoit sector and all the rest and look I probably don't have to tell you that understanding and remembering all of these is about as pleasant as having a gangrenous leg removed in the 18th century where your only option for anesthesia was a dirty Stick to bite on but stick with me and I'm going to try to explain it up real nice for you so if you're ready to get them brain cows milked let's get to it okay now before I start hurling Urban models your way let me give you a highlevel overview of why these are important like if we just start in with the models and they're going to be like a bunch of unfolded clothes on the flooor in your closet and nobody wants that so I'm going to try to build a closet first and then get some hangers and organize all that information okay first of all these models tell us about the internal structure of cities themselves now in previous videos for this unit we've talked about how and why cities are spatially arranged throughout the world and how they're related by interactions with one another what we have not talked about is why cities themselves are arranged in the way that they are in and of themselves like why is that Residential Building over there and not over there why is that government building over there and not over there and on and on and that's what these models seek to explain second you need to keep things real simple in your head and remember that every city is essentially only made up of three entities a central business district industrial or commercial district and residential location so each of the models are going to get progressively more complex but they're all riffing on this same three chord structure so to speak and finally let me tell you what you need to know about each of these models for your exam you will never see a question asking you to reproduce one of these models so you that's a release but now let me tell you about the things you will need to understand about these models first you're going to need to know the strength and limitations of each second you need to know how Innovations and transportation led to the new models third you're going to need to know why the different sectors are located where they are and the sector's relationship to each other and finally you need to understand how bid rent Theory helps explain the spatial arrangement of these models and in case you thought you could forget bid rent Theory let me just remind you that it says that land is most expensive in the central business district and then progressively decreases in cost the further you go from from the central business district okay then closet built and I reckon we're ready to get cozy with each of these seven models but before we do let me just mention that if you need help getting an A in your class and a five on your exam in May you might want to check out my AP Human Geography he review gu it's got whole uni review videos that you won't find here on YouTube no guides to follow along practice questions practice exams and answer keys to all of it so you know if that's something that you're into Link in the description OKAY model number one the Burgess concentric zone model before I explain it I should tell you that the first four models I'm going to show you are best for understanding the internal structure of cities mainly in North America so Burgess was the first to take a crack at it in the 1920s and he was studying Chicago in order to develop his model and so let's have a look so burges argue that a city develops and grows outward in uniform concentric circles radiating out from its Central business district so the first Circle represents the CBD and here you'll find the Central Transportation Hub of the city the headquarters of major businesses and financial institutions political offices and all the rest and then moving outward to Circle 2 also known as the zone of transition we observe mixed land use with with industrial centers and lowcost highdensity housing and in 1920s Chicago this is where the poorest Urban residents live then Circle 3 is where you find workingclass residential land use now this is where many of the industrial workers live since they had jobs and could afford it and it gave them good access to the industrial sector in circle two not to mention the services found in the CBD and then in Circle Four you have middle class residential land use now bid rent Theory says that the land is going to be cheaper here since it's further away from the CBD so the middle class will have larger homes on biger tracks of land and then in circle five we have upper class residential homes this is the Suburban commuter Zone that features expensive single family houses and so the Burgess model answers the question of the internal structure of cities like this the further from the CBD the cheaper the land becomes and thus the less dense the population becomes and that is exactly what bid rent Theory would say however the main limitation of this model is that it's just too dang tidy to fit reality just like every other model we've seen up to this point however to be fair when Burgess was observing Chicago in the 20s and 30s the model was pretty accurate for describing that particular City but once Railways and Automobiles became a more present reality for commuting this model became quickly dated all that to say the main limitation of this model is that it only considers distance from the CBD as the main reason the internal structure of cities are arranged the way that they are so that increasing complexity led us to our next model namely the hoit sector model now this model sought to address the shortcomings of the burges model by adding a second factor to explaining the internal structure of C remember burges only accounted for distance from the CBD whereas the hoit sector model adds Direction as a determining factor for the layout of urban areas or if you're sassy you could say that the hoit sector model describes the internal arrangement of a city in terms of transportation and communication so basically this model predicts that cities will develop not in concentric circles like bur just said but rather in wedge shaped sectors like you see here and why is that says you well says I these wedges correspond to major transportation routes and by 1939 when Hoy introduced this model the major transportation Innovation that drove this Urban structure was electric street cars and elevated trains both of which made it easier for people to commute to the CBD for work and for other services so there at the center is the CBD right where you'd expect it and then each wedge extends outward along various Transportation routes in this model lower income housing is still close to the industrial sector while middle and upper classes can afford to move further away from the CBD and then commute to the city center and the big difference between this and the Burgess model is that the various classes of residents build housing along the transportation routes instead of locating them in the concentric circles of the Burgess model okay now the main limitation of this model which is the limitation it shares with Burgess is that it assumes that cities develop in a fairly predictable manner the model predicts it that's how it's going to be but as it turns out reality is a little messier than that which leads us to our next model now the multiple nuclei model was developed in the 1940s to address the shortcomings of the hoit sector model which is to say cities don't generally conform to a uniform shape instead chony Harris and Edward Olman who developed this model argued that a city develops around several distinct nodes or nuclei of different functional regions therefore Urban Land Use isn't predictable across all cities but varies depending on the local context and again it was new Innovations and transportation that led to the need for a new model in this case the growing prevalence of automobiles okay so this model assumes that the CBD is not the central defining feature of land use but rather that growth occurs independently around several different focal points or nuclei in the previous two models the CBD was the big old node that defined how the rest of the land was going to be used but with highways being built and folks moving to the outskirts of urban areas other less sign ific nodes were created that lessened their dependence on the CBD and this is very much true in cities like Los Angeles California or Houston Texas for example so the question I'm sure is burning in your brain right now is this what determines the location and growth of those other nodes what an insightful question and as it turns out there are three factors that explain this first specialized activities required specialized land and infrastructure for example Urban industrial sites spring up where there is well-developed transportation infrastructure to support their operations second there can be economic benefits for related companies locating in financial sectors or business districts apart from the central business district and then third the negative consequences of industry and Commercial practices things like noise and pollution can lead to the creation of new nodes away from the CBD and Industrial sectors and mostly it's the affluent folks who can afford to move away from the CBD okay so the main limitation of this model is that over time the defined borders of the nuclei began to blend together with their surroundings so that distinct nuclei were more difficult to identify and wouldn't you know it those limitations led to the development of a fourth model to describe the internal structure of North American cities namely the galactic city model and as much as I wish I could tell you that this model was developed to describe how we're all going to end up living in most eely commuting to The Cantina and floating Speeders no in reality the galactic model was developed in response to Rising urban sprawl and the normalization of cars for commuting so here the influence of the CBD is decentralized and Suburban Edge cities develop which provide goods and services previously provided by the CBD but all parts of the city are connected through highways and people then use those belts to travel between the distinct Edge cities to take advantage of each settlement's unique offering and you can see this here in my fair city of Atlanta Georgia here's Interstate 285 which acts as a Beltway connecting the various Edge cities which have become well-developed nodes of Economic and residential land use apart from the CBD in downtown Atlanta and I happen to live in one of those Edge cities and if I can help it I almost never travel to Atlanta because the roads down there are a hot mess but thanks to this kind of Urban Development I don't really have any need to go to the city because everything I need is right here near my home so in this model there can be as many people employed in the suburbs as there are in the CBD or in some cases more and although this model still applies to many North American cities today a new limitation is becoming increasingly apparent this model is gradually becoming more obsolete with the rise of the internet which has given people access to shop and work from a distance therefore diminishing the importance of the Beltway connecting the edge cities okay now just a reminder those four models that we just ran through apply mainly to the development and structure of North American cities but last time I checked there are in fact other parts of the world and as it turns out these models don't do a great job of predicting the internal structure of those cities so wouldn't you know it three other models were developed to help explain those that I reckon we ought to talk about all right first among these models is the Latin American model which describes Urban growth in you know Latin America especially those areas that had previously been colonized by Spain and this model was specifically based on the structure of Mexico City now to understand this model you need to remember that Latin American cities have developed on their own since becoming independent of former Imperial Powers but that they still retain structural elements of colonial policy so in this model the location of the CBD and the market was established by Spanish law in the 16th century and it retains that same spatial Arrangement today now as you can see the Latin American model is a combination of concentric circles and wedge shaped zones the CBD is still Central but in this model it has two distinct areas the CBD is where businesses and entertainment venues are located but the market is where everyday goods are bought and sold and the spine here represents highquality Transportation infrastructure and on either side of it is where you'll find upper class housing then notice that the CBD is surrounded by the zone of maturity which is the location of middle class housing the next Zone known as the zone of Inu accretion is the space for lower inome housing but is considered a transitional zone between the poorest residents and the zone of maturity and finally the poorest Urban residents live here in the disamenity zones in the periphery and squatter residences known as baros and these are the places where little to know amenities exist things like you know police or running water okay now the next model to know is the Southeast Asian model which is also highly influenced by colonial policies of the past so here you can see that this wedge-shaped model is is not organized around a central business district but rather water-based trading ports established by former Imperial Powers also note that highclass residential isn't located at the edges like they are in the American models but rather they're close to the port and the government Zone Additionally you can see that the Suburban areas intermingle with the squatter areas in a way that's pretty different from the Latin American model and then one aspect unique to this particular model is the market gardening zone which accommodates light Agriculture and one particularly good example of a city conforming to this model is Manila which is the capital of the Philippines let's consider the last Model the subsaharan African model which predicts the internal structure of cities in you know subsaharan Africa so notice that this model has not one CBD but three a colonial CBD the traditional Marketplace and a modernizing CBD and then surrounding the CBD are many neighborhoods with distinct ethnic identities which are close to the Mining and Manufacturing Zone where many of them work and then the outermost circle is largely made up of impoverished Shanty towns and squatter settlement and a city that conforms pretty nicely to this model is Legos in Nigeria all right that was a beefy one so give a high five for making it all the way through you can click here to keep reviewing for unit 6 videos and you can click here to grab my AP Human Geography HBL review guide which has everything you need to get an A in your class and a five on your exam in May and hey I'll catch you on the flipflop I'm Lou