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" (CSAs). An earlier version of the MSA was the "Standard Metropolitan Statistical Area" (SMSA). MSAs are composed of counties and county-equivalents. In New England, because of the greater importance of towns over counties, similar areas are defined based on town units, known as New England City and Town Areas (NECTAs).

Definition issues

MSAs are delineated on the basis of a central urbanized area—a contiguous area of relatively high population density. The counties containing the core urbanized area are known as the central counties of the MSA. Additional surrounding counties (known as outlying counties) can be included in the MSA if these counties have strong social and economic ties to the central counties as measured by commuting and employment. Note that some areas within these outlying counties may actually be rural in nature.

MSAs are used for official purposes, but they are not the only estimates of metro area populations available. The appropriate boundaries - and therefore population figures - for some metro areas are much debated, and in some cases reputable sources provide figures which differ by millions. The most contentious examples include the Greater Los Angeles Area, the San Francisco Bay Area, and Greater Cleveland. However, some of these boundaries are addressed by CSAs. The official definitions used for the last U.S. Census differed from those for previous censuses, making comparisons difficult even between official figures at different dates (comparing 2000 with 1990, Baltimore was separated from Washington, D.C., but West Palm Beach was combined with Miami-Fort Lauderdale, which made a considerable difference to the rankings of both metros). Care should also be taken when comparing MSA figures with population figures for cities or metro areas outside the U.S., which may be based on substantially different boundary systems and definitions of terms. Additionally, United States MSA boundaries do not stretch into neighboring countries such as Canada or Mexico, so border cities such as Detroit, Buffalo, El Paso and San Diego would count only U.S. population figures.

As of June 2003, there is now an additional classification, that of a “Metropolitan Division.” The term metropolitan division is used to refer to a county or group of closely-tied contiguous counties that serve as a distinct employment region within a metropolitan statistical area that has a population core of at least 2.5 million. While a metropolitan division is a subdivision of a larger metropolitan statistical area, it often functions as a distinct social, economic, and cultural area within the larger region.

References

1. Census Geographic Glossary, U.S. Census Bureau

See also

• Geography
  • Human geography
    • Demography
• United States
  • United States Census Bureau
  • Office of Management and Budget
    • Combined statistical area
    • Core Based Statistical Area
      • Metropolitan Statistical Area
      • Micropolitan Statistical Area
    • Demographics of the United States
    • Table of United States Combined Statistical Areas (CSA)
    • Table of United States Core Based Statistical Areas (CBSA)
      • Table of United States Metropolitan Statistical Areas (MSA)
      • Table of United States Micropolitan Statistical Areas (µSA)
    • Table of United States primary census statistical areas (PCSA)
• List of metropolitan areas by population
• List of regions of the United States
• List of United States cities by population
• List of the largest metropolitan areas in the Americas
• List of the largest urban areas of the European Union by population
• Megacity
• World's largest cities

External links

• US Census Bureau Population Estimates
• Table 1. Annual Estimates of the Population of Metropolitan and Micropolitan Statistical Areas: April 1, 2000 to July 1, 2005
• U.S. Census 2000 Metropolitan Area Rankings; ranked by population
• U.S. Census 2000 Metropolitan Area Rankings
• Definitions of all Metropolitan Statistical Areas, Metropolitan Divisions
• U.S. Census Metropolitan Area Estimates (1990s)
• U.S. Census Metropolitan and Micropolitan Statistical Area Definitions