Beyond the suburbs, where once was countryside, a new ring of life encircles the nation's cities: the exurbs. In the exurbs, 20 percent of the workers commute into the city for work, the housing density is low and the population growth is high, according to the Washington-based Brookings Institution. In a study based on demographic and economic data from 1990 to 2005, the institute found that cities in the South and Midwest are hotbeds of exurban growth, while the West and Northeast remain more urban and suburban. In the South, 5 million people live in exurban communities, which is 47 percent of the nation's exurban population that, as of 2000, stood at 10.8 million.
Source: The Brookings Institute, Living Cities Census Series, October 2006