Urban structure and change

The central business district is the most accessible point in the city, because the main roads, railways and bus routes converge on the centre. This means the CBD can be reached easily by the largest number of people from all parts of the urban area.

Because so many people pass through it, the CBD is the most profitable location for shops, offices and services that depend on high footfall and good access. These businesses are therefore willing to bid the highest prices to locate there.

This competition for a limited amount of central land — the process of bid-rent — drives land values up to their highest level in the CBD. Land values then generally fall outward towards the edge of the city, where accessibility is lower and competition for sites is weaker.

One strength of the Burgess model is that it provides a simple, clear framework for understanding how land use is arranged. It correctly captures the general tendency for land value, building age and housing density to change with distance from the CBD — typically a commercial core surrounded by older, denser inner-city housing and then newer, lower-density suburbs further out. This makes it a useful starting point for comparing cities.

One limitation is that the model is a simplification based on an early twentieth-century North American city (Chicago) and assumes growth outward from a single centre on uniform land. Real cities rarely match this neatly: physical features such as rivers and relief distort the rings, transport routes pull land use into sectors (as Hoyt argued), and rapidly growing cities in lower-income countries often have wealthier housing near the centre and informal settlement at the edge — the opposite of the model.

The model is therefore best used as a generalisation to test against reality, not as an accurate map of any particular city.

The decline of a CBD is usually caused by the loss of activity to other locations. As retailing decentralised to out-of-town retail parks, where land is cheaper and parking is free, the CBD lost trade and footfall, leaving empty shops. At the same time, offices and services moved to business parks on the rural–urban fringe near motorway junctions, attracted by cheaper land and easier access. Rising competition for cramped, expensive central sites, traffic congestion and a lack of parking made the CBD less attractive, so investment fell and the area began to look run-down — worsening its perception and accelerating the decline.

Regeneration reverses this through investment and planning. Local and national planning decisions direct money into the centre: pedestrianisation, new covered shopping centres, cultural quarters, refurbished offices and new city-centre housing. 'Re-imaging' deliberately changes the perception of the CBD to draw people and businesses back. Improved public transport and reduced congestion restore accessibility.

The two phases are linked: it is precisely the decline — empty, low-value central sites — that creates the opportunity and the political will for regeneration. The combination of cost of land, transport provision, competition for space, investment and planning therefore drives first the decline and then the recovery of the CBD.

The rate of change in urban structure depends on the drivers acting on a city, and these differ strongly with economic classification.

In many higher-income countries, urban structure changes through decentralisation, deindustrialisation and regeneration. Manufacturing leaves the inner city, retailing moves out of town, and older centres are gradually regenerated. Because populations are often stable or slow-growing and planning systems are well established, change tends to be steady and managed rather than explosive.

In many lower-income countries, by contrast, very rapid rural-to-urban migration drives extremely fast change. Large numbers of in-migrants arrive faster than housing and services can be provided, so cities expand outward quickly, often with extensive informal settlement at the edge. With weaker or under-resourced planning, change is rapid and less controlled, and its direction differs — for example wealthier housing may remain near the centre while the poorest live on the periphery.

The location of a city and the strength of investment also matter: a well-connected city on a growth corridor with heavy investment changes faster than a remote one. Overall, the type and pace of change reflect the city's economic classification and the particular influences acting on it.

Residential zonation is the way the population of a city sorts into distinct residential areas with different characteristics — high-density inner-city housing, lower-density suburbs, high-status enclaves and, in some cities, informal settlement. The syllabus lists several causes: income, the supply of housing, ethnicity, planning, and cultural and historical factors. This essay assesses how far economic factors — chiefly income and the operation of the housing market — are the main cause, and argues that while income is the single strongest driver, it works alongside and through the other factors, so it is not the whole explanation.

The case for economic factors being dominant is strong. Income largely determines where people can afford to live: house prices and rents sort residents by ability to pay. Wealthier households buy space in desirable, leafy, low-density areas where prices are high, while lower-income groups concentrate in cheaper inner-city or older housing. Because the most accessible and pleasant sites command the highest prices, the market itself produces a broadly economic sorting of residential areas — the rich out-competing the poor for the best locations. In this sense income underlies much of the pattern, and many other 'causes' partly reflect it: an ethnic quarter is often also a low-income area because new migrants arrive with limited means. This supports the view that economics is the main cause.

However, residential zonation cannot be explained by income alone. The SUPPLY of housing strongly shapes the pattern: a district built as social housing, or as cheap terraces beside old factories, channels particular groups into it regardless of preference, and once that housing stock exists it fixes the zone for decades. ETHNICITY is a powerful, partly non-economic cause: people of the same cultural group cluster together for community, places of worship, familiar shops and language — and sometimes because of discrimination in the housing market — producing distinct ethnic quarters that persist even as incomes rise. These causes operate alongside income, not merely beneath it.

PLANNING and HISTORICAL/CULTURAL factors are also decisive and are not simply economic. Planning decisions deliberately place social housing, designate green belts and conservation areas, and steer regeneration, directly creating and constraining residential areas. Historical and cultural factors leave a lasting imprint: old workers' districts near former industry, long-established communities, and patterns set by past migration remain long after the original economic conditions have changed. A district may stay low-status or remain an ethnic quarter for generations through inherited reputation and community ties rather than current economics.

Most accurately, the causes interact, and income works partly THROUGH the others. Low income combined with a supply of cheap inner-city housing and an established ethnic community together produce a persistent, self-reinforcing residential zone — and the perception of that area then keeps similar groups arriving and others avoiding it. Economics sets the broad constraint of what people can afford, but housing supply, ethnicity, planning and history determine the detailed and durable pattern. To say economics is THE main cause therefore oversimplifies a multi-causal process.

In conclusion, economic factors — above all income — are the strongest single cause of residential zonation, because ability to pay broadly sorts the population across the city. But they are not the only cause: housing supply, ethnicity, planning and cultural/historical factors act alongside income and give zonation its detailed, persistent form. The most convincing assessment is that income provides the underlying framework while the other factors shape the actual mosaic, so residential zonation is best understood as multi-causal rather than primarily economic.

The Burgess concentric-zone model and the Hoyt sector model are simplified pictures of urban structure: Burgess shows land use as rings spreading outward from the CBD (CBD, inner city, suburbs, fringe), while Hoyt shows it as sectors radiating along transport routes. This essay assesses the claim that such models are of little value for understanding cities today, and argues that, although they are dated and simplified, they remain valuable as frameworks for organising and comparing urban structure — provided they are used as generalisations, not literal maps.

There is real force in the criticism. Both models are old — Burgess (1925) was based on Chicago and Hoyt (1939) on US cities — and they assume growth outward from a single centre on uniform land. Real cities depart from this in many ways. Physical features such as rivers, coasts and relief distort the neat rings. More importantly, the models predate the major changes of recent decades: retail and offices have DECENTRALISED to out-of-town parks and fringe business parks, manufacturing has left the inner city, and CBDs have declined and then regenerated — none of which a static ring or sector model captures. Above all, the models fit Western higher-income cities poorly when applied to rapidly growing cities in lower-income countries, where the wealthiest housing may lie near the centre and the poorest live in informal settlement on the periphery — the reverse of the Burgess pattern. To this extent the models can mislead.

However, the models retain considerable value. Burgess still captures a genuine and widespread tendency: land value, building age and housing density really do change with distance from the CBD in many cities, with a commercial core, older denser inner-city housing, and newer lower-density suburbs further out. Hoyt's insight that transport routes pull similar land uses into sectors remains visibly true — industry and lower-quality housing extend out along railways and main roads, while higher-status housing forms its own sector. Used together, the two models describe the real structure of many cities better than either alone: concentric zoning modified by sectoral wedges along the transport routes.

Their greatest value is as a STARTING POINT and a basis for comparison. A model gives students and planners a simple framework against which to test a real city — to identify where it fits and, more usefully, where and WHY it deviates. The act of explaining the exceptions (a regenerated waterfront, an out-of-town retail park, an informal settlement at the edge) deepens understanding precisely because there is a model to compare against. A framework that highlights what is unusual is far from valueless.

Most accurately, the models are limited but not worthless: their value depends on how they are used. Treated as literal descriptions of every modern city, they fail; treated as generalisations and comparators that must be modified for transport, recent decentralisation and economic classification, they remain a useful organising tool.

In conclusion, I largely disagree with the statement. Burgess and Hoyt are dated and oversimplified, and they describe rapidly changing and lower-income cities poorly, so they are certainly not accurate maps of cities today. But they retain real value as simple, comparable frameworks that capture genuine tendencies and, by exposing their own exceptions, help us understand why real cities are structured as they are. The models are therefore of limited but genuine value — useful generalisations rather than reliable blueprints.