Sociologists, economists, and geographers have developed three models to help explain where different types of people tend to live in an urban area—the concentric zone, sector, and multiple nuclei models. In addition, the galactic (or peripheral) model is a variation of the multiple nuclei model.

Concentric Zone Model

According to the concentric zone model, created in 1923 by sociologist Ernest Burgess, a city grows outward from a central area in a series of concentric rings, like the growth rings of a tree. Back in the 1920s, Burgess identified five rings (Figures 13-9 and 13-10). The precise number and width of the rings vary from one city to another, but the same basic types of rings appear in all cities in the same order.

Concentric Zone Model

Working-Class Homes

Inner-city Chicago.

Sector Model

According to the sector model, developed in 1939 by land economist Homer Hoyt, a city develops in a series of sectors (Figure 13-11). Certain areas of the city are more attractive for various activities, originally because of an environmental factor or even by mere chance. As a city grows, activities expand outward in a wedge, or sector, from the center.

Sector Model

Once a district with high-class housing is established, the most expensive new housing is built on the outer edge of that district, farther out from the center. The most expensive housing is therefore found in a corridor extending from downtown to the outer edge of the city. Industrial and retailing activities develop in other sectors, usually along good transportation lines.

High-Income Sector

Chicago’s North Side.

Multiple Nuclei & Galactic Models

According to the multiple nuclei model, developed by geographers Chauncey Harris and Edward Ullman in 1945, a city is a complex structure that includes a CBD (Figure 13-13) as well as other centers around which activities occur. Examples of these nodes include a port, a neighborhood business center, a university, an airport, and a park.

Chicago CBD

The multiple nuclei theory states that some activities are attracted to particular nodes, whereas others try to avoid them. For example, a university node may attract well-educated residents, pizzerias, and bookstores, whereas an airport may attract hotels and warehouses. On the other hand, incompatible land-use activities avoid clustering in the same locations. Heavy industry and high-class housing, for example, rarely exist in the same neighborhood.

Multiple-Nuclei Model

Node

The University of Chicago.

According to the galactic (or peripheral) model, developed by Harris in 1960, an urban area consists of an inner city surrounded by large suburban residential and service nodes or nuclei tied together by a beltway or ring road. Rather than an entirely new model, Harris considered the peripheral model to be a modification of the multiple nuclei model (which he co-authored), reflecting the growth of suburbs. The nodes of consumer and business services around the beltway are called edge cities.

Galactic (Peripheral) Model

Edge City

Donald E. Stephens Convention Center, Rosemont, Illinois, adjacent to O’Hare International Airport.

Pause & Reflect 13.2.1

If you cut down a large tree, which of the three models will the cross-section resemble? Why is the cross-section of a tree a good analogy for one of the models of urban structure?