(June 2003) As the U.S. population and jobs have grown less centralized, the task of measuring urban patterns has become more complex. Growing numbers of Americans and businesses are locating in smaller cities and towns, drawn by cheaper land, lower taxes, and less pollution and crime. Outer suburbs and “exurbs” — areas recently considered remote and rural — now are the sites of booming retail, industrial, and entertainment centers, often at the intersection of major highways.
Beginning in June 2003, the Office of Management and Budget (OMB) has instructed the Census Bureau to track “micropolitan” areas as well as metropolitan areas. Micropolitan statistical areas must have an urban cluster of at least 10,000 people but fewer than 50,000 people. The designation includes the county where the urban cluster is plus adjacent counties linked by commuting ties. The size and main criteria for metropolitan statistical areas are largely unchanged.
Since the 1950s, the OMB has defined a metropolitan statistical area (MSA) as an urban core of at least 50,000 people, the county in which it is located, and adjacent counties linked by commuting. The 2000 Census found that 80 percent of Americans lived in MSAs (or their equivalents) and 20 percent in nonmetropolitan counties.
These new distinctions mean that about 83 percent of people in the United States now call metropolitan areas home, while 10 percent live in micropolitan areas. Metropolitan and micropolitan areas are known together as “core based statistical areas.” Only 7 percent live in counties not linked to any urban area or urban cluster, termed “outside core based statistical areas.”
Because whole counties are used to create core based statistical areas, they encompass farms, ranchland, and forests. For this reason, OMB cautions against using the new definitions to make rural-urban distinctions.
Using the new definitions, applied to data from the 2000 Census, OMB lists a total of 362 MSAs, including 47 new ones such as Ames, Iowa; Bend, Ore.; Fairbanks, Alaska; and Sandusky, Ohio. The list also contains 560 micropolitan statistical areas, from Abbeville, La., and Aberdeen, S.D., to Yazoo City, Miss., and Zanesville, Ohio.
Simplified criteria now determine which counties are linked. An outlying county is economically tied to a metropolitan or micropolitan area when 25 percent of its residents work in the central city or, conversely, when 25 percent of the jobs in the outlying county are filled by workers from the central county or counties.
Adjacent core based statistical areas — either metropolitan or micropolitan in various combinations — are also designated as “combined statistical areas” if commuting patterns (using less stringent criteria than the ones used in determining metropolitan or micropolitan areas) link the two areas. There are 116 combined statistical areas of varying sizes. For example, the Las Vegas-Paradise, Nev., metropolitan statistical area and the Pahrump, Nev., micropolitan statistical area together form the Las Vegas-Paradise-Pahrump, Nev., combined statistical area.
Also under the new rules, areas with 2.5 million people are subdivided to form smaller groups of counties, called metropolitan divisions. For example, the Bethesda-Frederick-Gaithersburg, Md., metropolitan division is part of the larger Washington-Arlington-Alexandria, D.C.-Va.-Md.-W.Va., metropolitan statistical area.