A history of urban sprawl

We know that people in the United States have been moving to the edges of cities and metropolitan areas for centuries. See Robert Bruegann’s A Compact History of Sprawl or Dolores Hayden’s Building Suburbia for the details of this history.  Even the post World War II era saw several waves of suburban development development that Hayden characterized as sitcom suburbs and edge cities. The end of the century saw extreme commutes with a lot of development in what are now often referred to as exurbs.

But what we don’t know is how much sprawl has been occurring over the past many decades and whether these trends are continuing at a steady pace, accelerating, or decelerating. One very imprecise measure is the proportion of people living in suburbs versus center cities, but this tells us very little  because some suburbs are very dense and sone central cities contain large areas of low density development. For example, some suburbs are denser than their center cities: Somerville, MA and Daly City, CA are two.  Other cities, such as Phoenix and Houston, have very low density areas within their city limits (not to mention the issue with measures for consolidated cities an counties).

A problem with many sprawl measures is that they’re relative measures. Even if you could calculate them for multiple years, they would not tell you how sprawl changed in that particular metro area.

So one project I am working on is to calculate sprawl for every metro area for each census year from 1970 to 2010. This uses a measure developed by my colleague Pat Hynes and me that is based on the difference between the proportion of a metropolitan area’s high density and low density population. A measure I call the Density Balance Sprawl Index.

The results, almost ready for publication, will surprise many people. Stay tuned.

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