Internal Structure of Cities

Did you know towns and cities loosely follow patterns that determine where people live and work? Is there a logic to it? Yes! Since the 1900s, geographers have tried to make sense of where and why things are placed in cities. Cities were built differently all over the world, subject to changing times, politics, economies, or invasions! Still, a few models have attempted to describe and possibly predict how cities will grow, where people will live, and where businesses will locate. Let's dive into the internal structure of cities, the theories that form these internal structures, called bid-rent theory, and the different models that best explain them.

Internal Structure of Cities: Definition

The internal structure of cities is the way people, activities, and what links them are distributed. Their distribution can be explained by theories, models, and patterns. Generally, every urban land model has a central business district (CBD) at the center. The CBD is the area for the main business and commercial activity in a city. In other words, it's a city's "downtown" or "city center." The CBD can also serve as a central point for other major city functions such as transportation, and cultural and social functions.

Aside from the CBD, cities also have residential, manufacturing, and retail areas. Residential areas are where people live and reside. Manufacturing and industrial areas are involved in creating, processing, packaging, or distributing products to be sold on the market. Retail areas are usually interchangeable with the CBD and provide goods and services.

Internal structure of cities: Bid-Rent Theory

The Bid-Rent Theory explains where retail, manufacturing, and residential areas will spread according to the CBD. It explains how the demand, and as a result price, is highest at the CBD. The CBD can provide the highest concentration of access to markets and labor, and retailers are willing to pay the highest rent for that. Although locations farther away from the CBD are cheaper, transportation costs for both retailers and customers often reduce profits.

Fig. 1 - Bid Rent Curve

Although manufacturers also need access to markets and labor, it's still less of a concern than for retailers. The greater access to space also means wider land is needed, leading them to the outer cores of cities.

Finally, residents will move farther out of the city where land is the cheapest to buy or rent for housing. There are few retailers and manufacturing areas outside of the CBD and outer core, decreasing demand, and prices. People will then take up residence in those areas.

Internal Structure of US Cities

The internal structure of towns and cities can be generalized by theories and models, but each city has its own unique internal structure. Many cities have changed dramatically with the introduction of new technology, focus on services, and private car use.

In the US alone, cities are distinctly different depending on the time they were founded and urbanized. For instance, cities in the northeast were founded by Europeans before advancements in transportation were made. Therefore, similar to other European cities, grid-like streets with greater density were desired.

However, southern cities founded during the private car boom are built around car dependency as the main transportation method. This means cities are sprawling, with lower density and fewer walking options.

Models of Internal Structure of Cities

From the bid-rent theory, several city models can be observed. US cities are unique in that many were built during the growth of automobile ownership. As a result, there are some models that can only be applied in the US. Let's take a look at some different models and what they seek to explain.

Internal Structure of Towns and Cities

There are several models that explain the internal structure of cities. Cities and towns continue to change due to globalization and transportation changes, and some of these models are quite outdated now. However, it's still important to understand how cities began to form and how early geographers documented the changes.

Concentric Zone Model

Ernest Burgess developed his Concentric Zone Model in 1925. It was modeled after what he was witnessing in Chicago and is one of the first theoretical models to explain the distribution of urban land use. It's also the main model behind the bid-rent curve theory.

Fig. 2 - The Concentric Zone Model

Similarly to the bid-rent curve, the CBD is at the center with manufacturing in the outer core, and residential areas distributed throughout the rest of the area. A key difference is that the working class area is closer to manufacturing than wealthier residential areas. This is to explain where social and economic groups were more likely to move or cluster.

There are major critiques of this model now, however, as it can't be applied well to cities outside of the US. Changes in transportation and communication technology have also changed the distribution of land use, as people can freely commute with cars now.

Hoyt Sector Model

The Hoyt Sector Model was proposed in 1939 and builds on the Concentric Zone Model. Although it can be applied in British cities, it doesn't take into account the newest advancements in private car use. However, it's more applicable to older cities.

Fig. 3 - TheHoyt Sector Model

Hoyt's Sector Model focuses on wedges instead of rings. Residential and manufacturing areas are mixed with one another but still revolve around the CBD. With transportation and infrastructure changes in later years, suburbs change the applicability of this model.

Harris and Ullman Multiple-Nuclei Model

Harris and Ullman's multiple nuclei model was created in 1945, based on new technology changes in Chicago. A difference in this model is that multiple CBDs arise with their own purposes and unique economic opportunities. For instance, workers in manufacturing will live closer to those areas, while wealthier people will move away from polluted manufacturing zones. The model is largely based on economic segregation patterns that can be seen in many US cities.

Fig. 4 - Harris and Ullman's Multiple Nuclei Model

Though there are many other models, these three are at the core of urban geography in the US.

Internal Structure of Other Cities

Although there are models that best fit US cities and their changes, there are other cities in the world that don't fit that mold. That's due to the growth of cities during periods of Western colonialization and development. This applied to cities in Latin America, Africa, and Southeast Asia.

Latin American City Structure

Latin American city structures are a mix of the concentric model with colonial influences. The Griffin-Ford Model, created in the 1980s, encompasses the general patterns Latin American cities are built in.

Fig. 5 - The Griffin-Ford Model is an attempt to describe the layout of Latin American cities

The model begins with a CBD at the center, with a spine reaching out towards a mall. The spine also acts as its own CBD, with many major businesses located there. There are divisions based on socioeconomic classes, with the elite residential sector surrounding most commercial areas. The CBD, the spine towards the mall, and the elite residential sectors usually have the strongest infrastructure, as they are invested in the most.

While these are the main components of the model, there are also concentric zones surrounding these areas with decreasing living qualities farther from the center. The areas farthest from the CBD lack basic infrastructure, with informal squatter settlements surrounding the outside of the model. This is due to rapid urbanization, with many from rural areas moving into cities for increased access to opportunities and services.

African City Structure

African cities are also primarily influenced by European colonialization. The difference between African and Latin American city structures is that African cities are known for having three CBDs: a traditional open market, a European colonial center with grid-like streets, and a developing CBD. These CBDs are placed around the center of the model, with residential locations surrounding them.

These residential locations differ depending on the proximity to the CBD. There's more of a mix of socio-economic residents closer to the CBD. Manufacturing zones tend to surround these residential zones, where lower land costs allow for bigger industrial projects to build. After the manufacturing zones are squatter settlements along the outskirts of the cities. This is due to fast-growing populations and rapid urbanization. However, with rapid urbanization and development, much of this model is outdated.

Southeast Asian City Structure

Southeast Asian cities are also influenced by Western colonialism. Many countries sought to trade with these countries for raw materials and resources. As a result, many Southeast Asian cities are built around port zones. Where there's no traditional CBD, the port zone operates as a similar focal point.

There are other special zones as well, including government, western, and alien commercial zones. These areas are distributed across the city. Models of Southeast Asian cities also take into account the distribution of middle-income residents in the periphery or suburbs.