"Measuring Sprawl" by Witold Rybczynski, in Zell/Lurie Real Estate Review (Spring 2002), The Wharton School, Univ. of Pennsylvania, 256 S. 37th St., Philadelphia, Pa. 19104.

To many critics, urban sprawl is like landscape pornography: They know it when they see it, and they know where to look for it. Or do they? According to Rybczynski, a professor of architecture and urbanism at the University of Pennsylvania, those who decry sprawl as irresponsible growth and liken its haphazard and aggressive patterns to cancer may be guilty of misdiagnosis.

Conventional measures of population density—the number of inhabitants per square mile—largely confirm conventional notions of sprawl: Older metropolitan areas such as New York and Chicago sprawl the least, while cities in the South and West sprawl the most. But the picture changes when one takes into account how land is actually used. Metropolitan areas contain surprising amounts of acreage that is devoted to parkland or can’t be developed, such as mountain slopes and wetlands. Using a 1997 U.S. Department of Agriculture study of urbanized land (land used commercially, residentially, or recreationally), Rybczynski draws a "radically different" portrait of sprawl. Los Angeles, with 5,318 people per urbanized square mile, is the most densely populated city in the United States, followed closely by New York, Miami, and Phoenix. Philadelphia ranks a surprising tenth, not far ahead of Dallas, Houston, and least-dense Atlanta, which, with 1,818 people per urbanized square mile, remains the "poster child" for sprawl.

Moreover, U.S. Census Bureau data tracking changes in the population density of urbanized land from 1982 to 1997 yielded unexpected results: In the old industrial cities of the Northeast and Midwest, land urbanization occurred at twice the rate of population growth. Even though droves of Americans flocked to western and southern cities, land urbanization in those regions actually proceeded at a slower pace than population growth. New development was actually more sprawl-like in the older metropolitan areas.

So what’s behind sprawl? Disparities in land costs and the rate of population growth, argues Rybczynski. The localities consuming the most land are in the slow-growing Northeast and Midwest, possibly because the existing compact city centers there stimulate a greater demand for less-dense development. Conversely, geographical and water-resource constraints in the South and West have tended to restrict the amount of land available for development, and thus contributed to higher land costs. What really may be bothering the public, Rybczynski suspects, is not sprawl but rapid growth.