U.S. Census Bureau

Metropolitan and Micropolitan Statistical Area Definitions

The Office of Management and Budget (OMB) defines metropolitan and micropolitan statistical areas. Currently defined metropolitan and micropolitan statistical areas are based on application of the 2000 standards (which appeared in the Federal Register on December 27, 2000) to Census 2000 data, as updated by application of those standards to more recent Census Bureau population estimates. The current definition is as of December 2005.

Metropolitan and micropolitan statistical areas consist of one or more counties. The OMB defines a conceptually similar set of areas in New England using cities and towns as geographic building blocks, referred to as New England city and town areas (NECTAs).

If specified criteria are met, adjacent metropolitan and micropolitan statistical areas, in various combinations, may become the components of a new set of areas called combined statistical areas. The geographic components of combined New England city and town areas are individual metropolitan and micropolitan NECTAs, in various combinations. The areas that combine retain their own designations as metropolitan or micropolitan statistical areas (or NECTAs) within the larger combined statistical area (or combined NECTA).


Current Definitions (as of December 2005) based on July 1, 2003 and July 1, 2004 population estimates:


Previous Definitions

Metropolitan and micropolitan statistical areas defined as of November 2004 based on July 1, 2002 and July 1, 2003 population estimates:


Metropolitan and micropolitan statistical areas defined as of December 2003 based on July 1, 2001 and July 1, 2002 population estimates:


Metropolitan and micropolitan statistical areas defined as of June 6, 2003, based on application of the 2000 standards to Census 2000 data:



For more information, contact the Population Distribution Branch at (301) 763-2419.