The Shapes of Large Urban Areas in the U.S., 1950-2010: Patterns, Causes, and Consequences

Abstract

The compactness of the shapes of 59 large urban areas in the United States from 1950 to 2010 is measured using an index of proximity based on the mean distance from the Central Business District to all areas within the urban area. Average changes in the proximity index over time are small, but individual urban areas have experienced much larger changes in shape, becoming both more and less compact. Larger urban areas tend to be somewhat less compact. Barriers to the expansion of urban areas including water, wetlands, mountains, and protected lands are associated with lower levels of proximity and compactness. Lower proximity is associated with higher urban area densities and smaller declines in densities with distance from the Central Business District.