Metropolitan Statistical Area

In the United States, the Office of Management and Budget (OMB) has produced a formal definition of metropolitan areas. These are referred to as "Metropolitan Statistical Areas" (MSAs) and "Combined Statistical Areas." An earlier version of the MSA was the "Standard Metropolitan Statistical Area" (SMSA). MSAs are composed of counties[1]. In New England, because of the greater importance of towns over counties, similar areas based on town units, known as New England City and Town Areas (NECTAs), are additionally defined.
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(See also Central City, Standard Metropolitan Statistical Area) Areas defined by the U.S. Office of Management and Budget. A Metropolitan Statistical Area (MSA) is 1) A county or a group of contiguous counties that contain at least one city of 50,000 inhabitants or more, or 2) An urbanized area of at least 50,000 inhabitants and a total MSA population of at least 100,000 (75,000 in New England). The contiguous counties are included in an MSA if, according to certain criteria, they are essentially metropolitan in character and are socially and economically integrated with the central city. In New England, MSAs consist of towns and cities rather than counties. (DOE4) (DOE5) (FHWA3)