Density of Large Urban Areas in the U.S., 1950-2010

Density is a fundamental, defining characteristic of urban areas that has important implications for many other aspects of urban life. Using census tract data for 1950 to 2010, the extent of the built-up urban areas is delineated in a consistent manner for 59 of the largest metropolitan regions in the United States. Contrary to common expectations of nearly universal decline in urban densities, many areas showed relatively stable densities or even significant increases over the period. The areas with stable or increasing densities were located in the South and, especially for increases in density, in the West. The larger declines in densities occurred in areas in the Northeast and Midwest. Density levels and changes in density were associated with the sizes of areas, prior densities, rates of growth, and the presence of barriers to urban expansion.