Metropolitan Definition

The term Metropolitan has many definitions, and for the purposes of the Center we use the terms as defined by the U.S. Office of Management and Budget in OMB Bulletin NO. 23-01.

U.S. Office of Management and Budget Definitions

• Metropolitan Statistical Areas have at least one urban area of 50,000 or more population, plus adjacent territory that has a high degree of social and economic integration with the core as measured by commuting ties.
• Micropolitan Statistical Areas have at least one urban area of at least 10,000 but less that 50,000 population, plus adjacent territory that has a high degree of social and economic integration with the core as measured by commuting ties. Metropolitan and Micropolitan Statistical Areas are delineated in terms of while counties or county equivalents.
• Principal Cities are within each Metropolitan Statistical Area and Micropolitan Statistical Area and encompass both incorporated places and census designated places (CDPs). In addition to identifying the more significant places in each Metropolitan and Micropolitan Statistical Area in terms of population and employment, principal cities are also used in titling Metropolitan and Micropolitan Statistical Areas, Metropolitan Divisions, and Combined Statistical Areas.

Rural-Urban Continuum Codes (RUCC) adds nuance to the Metropolitan designation assigned to counties by the OMB. The RUCC is a classification scheme developed by the U.S. Department of Agriculture (USDA) Economic Research Service (ERS) that distinguishes metropolitan counties by the population size of their metro area, and nonmetropolitan counties by their degree of urbanization and adjacency to a metro area. It subdivides the official OMB metro and nonmetropolitan categories into three metro and six nonmetropolitan categories. Each county in the U.S. is assigned one of the 9 codes.

Under the RUCC scheme, the following codes differentiate metropolitan counties

1: Counties in metro areas of 1 million population or more
2: Counties in metro areas of 250,000 to 1 million population
3: Counties in metro areas of fewer than 250,000 population