The Most Famous Models for How Cities Grow Are Wrong
In the last hundred years, one of the most enduring models of urban development has been the iconic "concentric zones" map. Outlined by Chicago School sociologist Ernest Burgess, it was initially published in the classic 1925 volume The City, by Burgess and his University of Chicago colleague Robert Park.
This Chicago School model suggests that cities grow steadily outward from the urban core or central business district. Surrounding this commercial core is a "zone in transition," with factories and warehouses. Beyond this comes the tenements and apartments of the working class, next the middle-class neighborhoods of larger homes, and ultimately the affluent commuter zones.
How well has this model -- or, really, any model -- held up over the past century of urban growth?
It's a question that animated Andrew A. Beveridge, a professor of sociology at Queens College. Beveridge used detailed, census tract-level data on changing population density since 1910 to determine whether our patterns match up to existing theories. In addition to the Chicago School model, he considered two others:
- The Los Angeles model, based on the theories of urbanists from UCLA and USC, which argues that growth does not follow an orderly concentric pattern but, based on the experience of post-war L.A., occurs in a sprawling fashion, as a multiplicity of commercial, industrial and residential areas spread outward without noticeable pattern.
- The New York school, which Beveridge associates with Jane Jacobs and William Whyte, suggests that most economically productive districts and the most desirable residential areas are concentrated in and around the city’s dense center; growth in the periphery is less patterned.
Ultimately, Beveridge's interesting analysis found that the basic Chicago School pattern held for the early part of the 20th century and even into the heyday of American post-war suburbanization. But more recently, the process and pattern of urban development has diverged in ways that confound this classic model.
The maps (below) from his study below contrast changes of density of these major metros for the earliest decade available – in Chicago and New York from 1910 to 1920, and in Los Angeles from 1940 to 1950.
The pattern of urban growth and decline has become more complicated in the past couple of decades as urban centers, including Chicago, have come back. "When one looks at the actual spatial patterning of growth," Beveridge notes, "one can find evidence that supports exponents of the Chicago, Los Angeles and New York schools of urban studies in various ways." Many cities have vigorously growing downtowns, as the New York model would suggest, but outlying areas that are developing without any obvious pattern, as in the Los Angeles model.
The second set of maps (below) get at this, comparing Chicago in the decades 1910-20 and 1990-2000. In the first part of the twentieth century, decline was correlated with decline in adjacent downtown areas, shown here in grey. Similarly, growth was correlated with growth in more outlying suburbs, shown here in black. In the earlier period growth radiated outwards -- a close approximate of the Chicago school concentric zone model. But in the more recent map, growth and decline followed less clear patterns. Some growth concentrated downtown, while other areas outside the city continued to boom, in ways predicted more accurately by the New York and Los Angeles models. The islands of grey and black--which indicate geographic correlations of decline and growth, respectively--are far less systematic. As Beveridge writes, the 1990-2000 map shows very little patterning. There were "areas of clustered high growth (both within the city and in the suburbs), as well as decline near growth, growth near decline, and decline near decline."
The emerging post-industrial city and metropolis increasingly confound the classic models and images we use to explain urban development.
On the on hand, the ongoing "back to the city" is bringing middle class people back to the core, and shifting poverty to the the suburbs, a process Alan Ehrenhalt dubs "the great inversion." But we are also seeing increasingly divided cities, and inequality that has not existed before. This is something I have explored in my series of posts on class-divided cities. Important studies by Robert Sampson and Patrick Sharkey note that as inequality has grown, and once high-paying manufacturing jobs have disappeared, our economy and labor market has divided. Those with more high paying knowledge jobs have clustered in and around the core, and a much larger number of low-wage service workers have been pushed to the outskirts of both urban and suburban knowledge zones.
The post-industrial city and metropolis is evolving as a patchwork of concentrated and persistent disadvantage alongside concentrated and increasingly self perpetuating advantage.
Top Image: Ernest Burgess's Concentric Zones, first published in The City in 1925.