A metropolitan or micropolitan statistical area's geographic delineation, or list of geographic components at a particular point in time, is referred to as its "definition." Metropolitan and micropolitan statistical areas are defined by the U.S. Office of Management and Budget (OMB) and are the result of the application of published standards to Census Bureau data. The standards for defining the areas are reviewed and revised once every ten years, prior to each decennial census. Generally, the areas are redefined using the most recent set of standards following each decennial census. Between censuses, the definitions are updated annually to reflect the most recent Census Bureau population estimates. Areas based on the 2000 standards and Census 2000 data were defined in June of 2003. The current definitions are as of November 2007.
The files below show definitions of metropolitan and micropolitan statistical areas and related statistical areas defined by OMB since June 2003. Related statistical areas include New England City and Town Areas (NECTAs), which are conceptually similar to metropolitan and micropolitan statistical areas, but are defined using cities and towns instead of counties; Combined Statistical Areas, which are aggregates of adjacent metropolitan or micropolitan statistical areas that are linked by commuting ties; and Combined New England City and Town Areas, which are aggregates of adjacent NECTAs that are linked by commuting ties.
For definitions of metropolitan areas prior to 2003, see the historical definitions page.
|Metropolitan and micropolitan statistical areas and components|
|Principal cities of metropolitan and micropolitan statistical areas|
|Counties with metropolitan and micropolitan statistical area codes|
|Metropolitan statistical areas and components|
|Micropolitan statistical areas and components|
|Combined statistical areas and components|
|New England city and town areas (NECTAs) and components|
|Principal cities of New England city and town areas areas|
|Cities and towns with NECTA and Combined NECTA codes|
|Metropolitan NECTAs and components|
|Micropolitan NECTAs and components|