Sprawl: the new manifest destiny?

Abstract

Seen from 400 miles above the Earth, the greater Washington, D.C.– Baltimore area is an aggressive consumer of farmland and open spaces. Computer-enhanced satellite images of the area show paved surfaces as crimson tentacles, pushing steadily out from the urban core. Recent studies by the National Aeronautics and Space Administration now suggest the land area occupied by Washington, D.C., and surrounding communities will expand 80% over its current size by 2030. Urban sprawl so extensive that you can watch it from space is hardly limited to the nation’s capital. Indeed, sprawl—defined as low-density development that outpaces population growth—is endemic throughout much of the United States. Donald Chen, executive director of Smart Growth America, a nonprofit research coalition in Washington, D.C., says that the overall declines in urban density, loss of open spaces, and increased auto use that accompany sprawl are continuing “virtually unabated.” Those who leave cities for the suburbs may expect a healthier, cleaner environment, but sprawl developments actually present a range of health risks including poor air quality from rising vehicle use, watershed pollution, and a built environment that limits opportunities to walk from homes to businesses and schools, thereby exacerbating obesity and related medical problems, such as heart disease. Sprawl first surfaced as a federal policy issue in the late 1990s, driven mainly by then–vice president Al Gore, who made it a centerpiece of his environmental platform. Researchers were increasingly aware that sprawl was a growing problem fraught with economic, ecologic, and, possibly, health consequences. However, these consequences were not well understood, says Reid Ewing, an associate and research professor at the University of Maryland National Center for Smart Growth Research and Education. “Sprawl was mainly a political issue back then,” he recalls. “There were various hypotheses about the magnitude of sprawl and its impacts, but sprawl had been neither measured in a sophisticated way nor related objectively to a range of outcomes such as loss of farmland and increased air pollution.” Since the turn of the millennium, Ewing says, numerous studies have sought to quantify sprawl, define its causes, and investigate its health and environmental concerns. At the same time, alternatives to sprawl have been studied and applied in many areas, with varying levels of success.