March 4, 2008

Sac State expert finds that auto use is
not a major cause of urban sprawl

A study by a Sacramento State expert on public policy concludes that reduced auto use has very little effect on the phenomenon of urban sprawl. That means policy makers concerned with limiting urban sprawl should focus less on getting people out of automobiles and instead consider direct regulations and planning interventions that limit the amount of developable land in urban areas, concluded Sacramento State professor of public policy and economics Rob Wassmer.

Wassmer’s study, Causes of Urban Sprawl in the United States: Auto Reliance as Compared to Natural Evolution, Flight from Blight, and Local Revenue Reliance, will be published in the Fall 2008 Journal of Policy Analysis and Management.

Wassmer’s report is based on an elaborate statistical analysis of various proffered causes of sprawl, and concludes that a 10 percent reduction in households owning one or more cars would reduce the geographical size of an urban area by only 0.5 percent, and increase population density by only 0.7 percent. Those impacts are far smaller than those produced by other causes of sprawl, the study found.

“Natural evolution” or changes caused by natural economic factors, along with “flight from blight,” or people leaving to escape the real and perceived blight of the central places in urban areas, play much greater roles in generating sprawl, Wassmer’s analysis found.

A reduction in per capita income, an increase in the percentage of wealthy households, and a reduction in the percent of an urban area’s central places that are poor, all have demonstrably greater effects on controlling sprawl than reduced automobile use, he concluded.

“If differences in land use patterns across United States urban areas are only minimally influenced by auto reliance, the more appropriate policy to reduce sprawl is one that attempts to directly change land use,” the report concludes. “Land use is largely the cause of auto use, not the other way around.”

The entire study can be found at For more information, contact Wassmer at (916) 278-6304. For media assistance, contact Sacramento State’s Public Affairs office at (916) 278-6156.