AN EFFORT 10 YEARS IN THE MAKING HAS RESULTED in a redesign of the way the federal government classifies metropolitan areas. In light of population shifts, metro areas will no longer be compared using such terms as consolidated metropolitan statistical areas (CSMAs), primary metropolitan statistical areas (PSMAs), and metropolitan statistical areas (MSAs). In their place, the federal Office of Management and Budget has defined 361 metropolitan statistical areas and 573 micropolitan statistical areas that can be grouped into 123 combined statistical areas.

Among the other changes noted in The Brookings Institution's report, “Tracking Metropolitan America into the 21st Century”:

  • The new micropolitan and metropolitan statistical areas together “encompass 93 percent of the U.S. population and 46 percent of its land area.” The earlier definitions captured 80 percent of the population and just 20 percent of the land area.
  • The territory and population of 80 percent of the nation's largest metropolitan areas have changed.
  • The number of metropolitan areas with populations of more than 1 million drops from 61 to 49; the number of metropolitan areas with populations of less than 250,000 rises from 149 to 195.

    • Keep 'Em Straight

    Here are a few of the definitions you'll want to know to more ably compare data across the country:

    Micropolitan Statistical Area: A region containing at least one urban area with a population of 10,000 to 50,000.

    Metropolitan Statistical Area: A region containing at least one urban area with a population of at least 50,000.

    Combined Statistical Area: Represents two or more adjoining metropolitan or micropolitan statistical areas.