The concentric zone model draws the city as rings of growth around downtown

The ones that followed, by Homer Hoyt and by Harris and Ullman, are easiest to learn as corrections to it.

Five rings from the CBD outward

The concentric zone model has five zones. At the center sits the central business district, with offices, department stores and the highest land values. Next comes the zone in transition, where factories mix with run down housing and newly arrived immigrants find cheap rooms. The third ring holds working class families who want to live near their jobs. The fourth is a middle class residential zone with larger houses. The outer ring is the commuter zone of suburbs tied to downtown by rail.

Invasion and succession push each ring outward

Ernest Burgess belonged to the Chicago school of sociology, which borrowed ideas from plant ecology. As the city grows, the CBD expands into the zone in transition, newcomers press into the working class ring, and households that can afford it move one ring farther out. Sociologists called this invasion and succession. Land value explains the order too. Under bid rent theory, businesses pay most for central access, so homes take the cheaper land farther out.

Hoyt sectors and Harris and Ullman nuclei

In 1939 Homer Hoyt proposed the sector model, in which cities grow in wedges along transport lines rather than in rings. A high rent sector extends outward along a favored corridor, while industry follows a rail line or river. In 1945 Chauncy Harris and Edward Ullman proposed the multiple nuclei model, in which a car based city grows around several centers, such as a university, an airport or a suburban business district. Burgess has one center and rings, Hoyt one center and wedges, Harris and Ullman many centers.

In this model the poorest live near the center

The most common mistake puts the poor on the edge of the city. In the Burgess model the reverse holds. The lowest income residents crowd into the zone in transition beside the CBD, and income rises toward the commuter zone. Students mix this up with the Latin American city model, where wealthy families live near the center along a spine and squatter settlements ring the edge. A question that shows poverty on the outskirts is pointing away from Burgess.

Strengths and limits of a 1920s model

The model fits the American industrial city before mass car ownership, when people walked or rode streetcars and the center held most jobs. Its limits come from the same source. It ignores physical features, assumes a single center, and says little about cities outside North America. Chicago itself sits on Lake Michigan, so its real rings are half circles. Pair the model with site and situation when a question asks why a real city departs from it.

How the exam asks about city models

Free response questions often show a diagram, ask you to identify the model, then ask for one strength or limitation in a named context. Name the model, point to its shape, and connect one feature to a real cause, such as streetcar commuting or high land values near downtown. Photograph your three model sketches and let photo to quiz turn them into identification questions. The Unit 6 page and the von Thunen model help you compare urban and rural rings.

Last updated: 2026-10-03 · Written with AI assistance and reviewed before publishing.