Metropolitan statistical area

Due to suburbanization, the typical metropolitan area is polycentric rather than being centered around a large historic core city such as New York City or Chicago. Some metropolitan areas include more than one large historic core city; examples include the Dallas–Fort Worth metroplex, Virginia Beach–Norfolk–Newport News (Hampton Roads), Riverside–San Bernardino (Inland Empire), and Minneapolis–St. Paul (Twin Cities).

MSAs are defined by the Office of Management and Budget (OMB), which is part of the Executive Office of the President, and are used by the U.S. Census Bureau and other U.S. federal government agencies for statistical purposes.

Definitions

The U.S. Office of Management and Budget defines a set of core-based statistical areas (CBSAs) throughout the country, which are composed of counties and county equivalents.

CBSAs are delineated on the basis of a central contiguous area of relatively high population density, known as an urban area. The counties containing the core urban area are known as the "central counties" of the CBSA; these are defined as having at least 50% of their population living in urban areas with at least 10,000 residents. Additional surrounding counties, known as "outlying counties", can be included in the CBSA if these counties have strong social and economic ties to the central county or counties as measured by commuting and employment. Outlying counties are included in the CBSA if 25% of the workers living in the county work in the central county or counties, or if 25% of the employment in the county is held by workers who live in the central county or counties.

Adjacent CBSAs are merged into a single CBSA when the central county or counties of one CBSA qualify as an outlying county or counties to the other CBSAs. One or more CBSAs may be grouped together or combined to form a larger statistical entity known as a combined statistical area (CSA) when the employment interchange measure (EIM) reaches 15% or more.

CBSAs are subdivided into MSAs (formed around urban areas with at least 50,000 in population) and micropolitan statistical areas (μSAs), which are CBSAs built around urban areas with at least 10,000 but fewer than 50,000 in population. Some metropolitan areas may include multiple cities with populations below 50,000, but combined have over 50,000 people. Previous terms that were used to describe these regions include "standard metropolitan statistical area" (SMSA) and "primary metropolitan statistical area" (PMSA). Metropolitan statistical areas containing over 2.5 million people can also be further divided into metropolitan divisions.

On January 19, 2021, OMB submitted a proposed regulation for public comment to increase the minimum population required for an urban area to be designated as a metropolitan statistical area from 50,000 to 100,000. It ultimately decided to keep the minimum at 50,000 for the 2020 cycle.

On July 21, 2023, the Office of Management and Budget released revised delineations of the various CBSAs in the United States.