Over the past 50 years, the spatial pattern of urban development in the United States has featured two distinct trends. On the one hand, employment and population growths have heavily favored medium and large metropolitan regions over nonmetropolitan areas but, within metropolitan regions, most have occurred in low-density development at the fringe of urbanized areas. The thinning out of core areas and the extension of the fringe via low-density development have been pervasive.

The Costs of Sprawl was a pioneering research project, conducted by Real Estate Research Corporation (RERC) in 1974. This often-cited study was one of the first to address costs associated with spread-out, lower-density, urban development in comparison to more concentrated development patterns. After more than two decades of continued suburbanization in the United States, the concerns of the RERC study are still current, but the findings are outdated. In addition, the study context needs to be broadened because the RERC study was largely confined to the costs of infrastructure at differing density levels. While RERC acknowledged some environmental and social costs of sprawl, it did not address these matters in depth, nor did it consider the benefits of sprawl that accrue to individuals and communities.

A variety of studies have been conducted during the past 20 years to investigate the impacts of alternative land development patterns on transportation requirements, transit viability and productivity, environmental quality, economic productivity, and social equity. However, the issues are far from settled, in part because findings from some of the studies are in conflict, and questions have been raised about the methods applied and the data used. Numerous concerns about the real costs of sprawl, compared with the benefits many Americans attach to this pattern of development, remain to be addressed.

Some studies have concluded that low-density sprawl development is responsible for auto dependence and resulting traffic congestion and air pollution; high costs of infrastructure, such as water lines, sewer lines, and roads; loss of open space, prime agricultural lands, and ecologically important natural resources; and segregation of people along income and racial lines. These studies have further found that, because of a defective pricing system, many of the costs of sprawl are largely hidden to individual consumers and are instead borne by society at large. Some of these studies argue for public policies that encourage compact growth at higher densities within and contiguous to existing developed areas, with transportation investments and pricing policies coordinated to support such development patterns.

Other studies have countered that the costs of sprawl have been exaggerated and its benefits have been overlooked. These studies conclude that both residents and businesses choose to locate in low-density development because of its greater convenience, efficiency, safety, and amenities. Further, these studies argue that there are better responses to problems of traffic congestion, air pollution, and infrastructure finance than seeking to control land use patterns and limit auto use.

Clearly, the studies need to be reevaluated, the data updated, and a fresh look taken at this complex and controversial subject. Numerous questions must be thoroughly addressed to bring greater clarity to the subject: (1) What are the known and suspected costs and benefits of sprawl, both to the individual and to society? (2) What are the methods of assessing impacts, and what is the effectiveness of each? (3) What are the gaps and inconsistencies in existing data and research? (4) What do current trends portend? (5) What additional research is needed?

Until clearer answers to these questions are available, the appropriateness and consequences of federal, state, regional, and local policies promoting particular growth patterns and related transportation policies and investments will be uncertain.

The objective of this project is to produce current and useful information with supporting facts, theory, and analysis on the positive and negative impacts of sprawl on the U.S. economy, environment, and society, with an emphasis on transportation. The results of this project should benefit three audiences: the transportation communities, public officials and decision makers, and the general public. As a TCRP project, it is important that the role of public transportation policy, programs, and pricing systems be covered.

Status: The project is complete.

Product Availability: The findings from Phase I have been published as TCRP Report 39. The final report for the project has been published as TCRP Report 74.