Metropolitan Areas Cartographic Boundary Files Descriptions and Metadata

Boundary File Titles	1999 Metropolitan Areas & Central Cities
	1998 Metropolitan Areas
	1996 Metropolitan Areas
	1990 Metropolitan Areas
	2000 New England County Metropolitan Areas

The general concept of a metropolitan area (MA) is one of a large population nucleus, together with adjacent communities that have a high degree of economic and social integration with that nucleus. Some MAs are defined around two or more nuclei.

The MAs and the central cities within an MA are designated and defined by the federal Office of Management and Budget (OMB), following a set of official standards that are published in a Federal Register Notice. These standards were developed by the interagency Federal Executive Committee on Metropolitan Areas, with the aim of producing definitions that are as consistent as possible for all MAs nationwide.

Each MA must contain either a place with a minimum population of 50,000 or a U.S. Census Bureau-defined urbanized area and a total MA population of at least 100,000 (75,000 in New England). An MA contains one or more central counties. An MA also may include one or more outlying counties that have close economic and social relationships with the central county. An outlying county must have a specified level of commuting to the central counties and also must meet certain standards regarding metropolitan character, such as population density, urban population, and population growth. In New England, MAs consist of groupings of cities and towns rather than whole counties.

The territory, population, and housing units in MAs are referred to as "metropolitan." The metropolitan category is subdivided into "inside central city" and "outside central city." The territory, population, and housing units located outside territory designated "metropolitan" are referred to as "nonmetropolitan." The metropolitan and nonmetropolitan classification cuts across the other hierarchies; for example, generally there are both urban and rural territory within both metropolitan and nonmetropolitan areas.

To meet the needs of various users, the standards provide for a flexible structure of metropolitan definitions that classify each MA either as a metropolitan statistical area (MSA) or as a consolidated metropolitan statistical area (CMSA) divided into primary metropolitan statistical areas (PMSAs). In New England, there also is an alternative county-based definition of MSAs known as the New England County Metropolitan Areas (NECMAs). Documentation of the MA standards and how they are applied is available from the Population Distribution Branch, Population Division, U.S. Census Bureau, Washington, DC 20233-8800, telephone (301) 457-2419.

Metropolitan statistical areas (MSAs) are metropolitan areas (MAs) that are not closely associated with other MAs. These areas typically are surrounded by nonmetropolitan counties (county subdivisions in New England).

If an area that qualifies as a metropolitan area (MA) has more than one million people, two or more primary metropolitan statistical areas (PMSAs) may be defined within it. Each PMSA consists of a large urbanized county or cluster of counties (cities and towns in New England) that demonstrate very strong internal economic and social links, in addition to close ties to other portions of the larger area. When PMSAs are established, the larger MA of which they are component parts is designated a consolidated metropolitan statistical area (CMSA). CMSAs and PMSAs are established only where local governments favor such designations for a large MA.

In each metropolitan statistical area and consolidated metropolitan statistical area, the largest place and, in some cases, additional places are designated as "central cities" under the official standards. A few primary metropolitan statistical areas do not have central cities. The largest central city and, in some cases, up to two additional central cities, are included in the title of the metropolitan area (MA); there also are central cities that are not included in an MA title. An MA central city does not include any part of that place that extends outside the MA boundary.

The title of a metropolitan statistical area (MSA) contains the name of its largest central city and up to two additional place names, provided that the additional places meet specified levels of population, employment, and commuting. Generally, a place with a population of 250,000 or more is in the title, regardless of other criteria.

The title of a primary metropolitan statistical area (PMSA) may contain up to three place names, as determined above, or up to three county names, sequenced in order of population size, from largest to smallest. A consolidated metropolitan statistical area (CMSA) title also may include up to three names, the first of which generally is the most populous central city in the area. The second name may be the first city or county name in the most populous remaining PMSA; the third name may be the first city or county name in the next most populous PMSA. A regional designation may be substituted for the second and/or third names in a CMSA title if local opinion supports such a designation and the federal Office of Management and Budget (OMB) deems it to be unambiguous and suitable.

The titles for all metropolitan areas (MAs) also contain the U.S. Postal Service's abbreviation for the name of each state in which the MA is located. Each MA is assigned a four-digit Federal Information Processing Standards (FIPS) code, in alphabetical order nationwide. If the fourth digit of the code is "2," it identifies a CMSA. Additionally, there is a separate set of two-digit FIPS codes for CMSAs, also assigned alphabetically.

New England county metropolitan areas (NECMAs) are defined as a county-based alternative to the city- and town-based New England metropolitan statistical areas (MSAs) and consolidated metropolitan statistical areas (CMSAs). The NECMA defined for an MSA or a CMSA includes:

Central cities of a NECMA are those places in the NECMA that qualify as central cities of an MSA or a CMSA. NECMA titles derive from the names of these central cities. Each NECMA is assigned a four-digit Federal Information Processing Standards (FIPS) code.

Title	1999 Metropolitan Statistical Areas
Location	http://www.census.gov/geo/www/cob/ma1999.html
Geography	National File
Vintage	January 1, 1999
Formats	ARC/INFO Export (.e00), Arcview Shapefile, and ARC/INFO Ungenerate (ASCII)
Projection	Geographic (Lat/Lon)
Datum	NAD83
Distributor	Department of Commerce, Census Bureau, Geography Division
Originator	Department of Commerce, Census Bureau, Geography Division