Urban sprawl has sparked a national debate over land-use policy. At least 19 states have established either state growth-management laws or task forces to protect farmland and open space. Dozens of cities and counties have adopted urban growth boundaries to contain development in existing areas and prevent the spread of urbanization to outlying and rural areas. The Clinton administration has proposed to make urban sprawl a federal issue.
Although a clear definition of sprawl remains elusive, public debate over sprawl is driven primarily by general concerns that low-density residential development threatens farmland and open space, increases public service costs, encourages people and wealth to leave central cities and degrades the environment.
However, evidence suggests that suburbanization – which might be defined as urban-like development outside central urban areas – does not significantly threaten the quality of life for most people and that land development can be managed more effectively through real-estate markets than comprehensive land-use planning.
Are Open Spaces Threatened? Historically, the most rapid rate of suburbanization occurred between 1920 and 1950. By the 1970s and 1980s, the trend was moderating, according to a study of more than 300 fast-growth rural counties. Despite widely cited reports on the pace of urban growth, urban land remains a very small part of overall land use, and urban development does not threaten the nation's food supply.
- Less than 5 percent of the nation's land is developed and three-quarters of the population lives on 3.5 percent of the land [ see Figure I ].
- Only about one-quarter of the farmland loss since 1945 is attributable to urbanization.
- Predictions of future farmland loss based on past trends are misleading because farmland loss has been moderating since the 1960s, falling from a 6.2 percent decline in farmland per decade in the 1960s to a 2.7 percent decline in the 1990s.
- In addition, with dramatic increases in agricultural output, American farmers are producing almost 50 percent more food than in 1970, using less land.
Rural parks and wildlife areas have increased as dramatically as urbanized land.
- More than three-quarters of the states have more than 90 percent of their land in rural uses, including forests, cropland, pasture, wildlife reserves and parks.
- Acreage in protected wildlife areas and rural parks exceeds urbanized areas by 50 percent.
Does Suburban Growth Increase Public Service Costs? Many studies of the cost of development exaggerate the effects of suburbanization on local government costs. Most costs are recovered through on-site improvements made by developers. Local governments often do make conscious policy decisions not to recover the full costs of development, when officials and voters decide for one reason or another to subsidize development through general revenues. The evidence is mixed on infrastructure costs and whether low-density development causes them to increase. While some infrastructure costs (street maintenance, for example) fall as density increases, as a rule increases in density are accompanied by increases in population and in the level of general spending.
Is Suburban Growth Responsible for the Decline of Cities? Sprawl has been blamed for the decline of big cities and older, inner-ring suburbs. But while large cities have a number of features that attract businesses and people – roads, cultural activities, diverse and sometimes inexpensive housing opportunities and easy access to mass transit – many cities suffer from poorly functioning school systems, high tax rates, anticompetitive regulations and deteriorating housing stock. Studies show that for many families, particularly working-class families, the poor quality of central city schools is the driving factor in their moves to the suburbs. Concerns about public safety in general and crime in particular also drive many people from cities.
Does Suburban Growth Damage the Environment? Some critics of low-density residential development maintain that it means more pollution, more congestion and fewer preserved natural resources. They believe that higher-density compact development would mitigate those impacts. However, population density does little to alleviate auto-caused smog. As Figure II shows, metropolitan areas with the lowest population densities have the fewest air pollution problems. Furthermore, population density or compactness has little relationship to how much commuters depend on automobiles.
- More than 75 percent of commuter trips are by car in every area except New York – and more than 90 percent are by car in the vast majority of areas.
- Studies show that the number of vehicle miles traveled actually increases with population density in the United States.
Thus a policy strategy that attempts to increase population density could lead to more traffic congestion, exacerbating air pollution levels and potentially causing more areas to fail to meet federal clean air goals.
Another important environmental objection to suburbanization, the potential loss of open space, overlooks the fact that limiting development often accelerates the loss of open space inside urban areas. To overcome the shortage of land, developers eventually do projects on odd-shaped parcels and other lands that would ordinarily have remained vacant lots and the equivalent of mini-parks. In addition, plans to increase populaton density may call for the destruction of most farmland inside an area selected for high-density development, reducing urban open space still further.
Can We Trust Policy Planners to See the Future? Policy recommendations using a 20-, 30- or 50-year vision for a state or community inevitably adopt top-down planning tools and government control of land to achieve state policy goals. However, there is little evidence that governments are better suited than real estate markets and private conservation efforts to provide the kinds of homes and communities people want. Indeed, many planners have acknowledged that "bad planning" (for example, large-lot zoning) was a significant contributor to the urban sprawl they now want to eliminate. Ironically, many reformers expect state and local governments to operate differently once the "right" urban planning reforms are in place.