In the United States, a metropolitan statistical area (MSA) is a geographical region with a relatively high population density at its core and close economic ties throughout the region. Such regions are not legally incorporated as a city or town would be and are not legal administrative divisions like counties or separate entities such as states. As a result, sometimes the precise definition of a given metropolitan area will vary between sources. The statistical criteria for a standard metropolitan area were defined in 1949 and redefined as a metropolitan statistical area in 1983.
United States micropolitan statistical areas, as defined by the Office of Management and Budget (OMB), are labor market and statistical areas in the United States centered on an urban cluster with a population of at least 10,000 but fewer than 50,000 people. The micropolitan area designation was created in 2003. Like the better-known metropolitan statistical areas, a micropolitan area is a geographic entity used for statistical purposes based on counties and county equivalents. On July 21, 2023, the Office of Management and Budget released revised delineations of the various CBSAs in the United States, which recognized 542 micropolitan areas in the United States, four of which are in Puerto Rico.
Combined statistical area (CSA) is a United States Office of Management and Budget (OMB) term for a combination of adjacent metropolitan (MSA) and micropolitan statistical areas (μSA) across the 50 U.S. states and the territory of Puerto Rico that can demonstrate economic or social linkage. CSAs were first designated in 2003. OMB defines a CSA by various combinations of adjacent metropolitan and micropolitan areas with economic ties measured by commuting patterns. CSAs retain their own designations as metropolitan or micropolitan statistical areas in their respective larger combined statistical areas.
Pennsylvania has 14 U.S. Census Bureau-designated metropolitan statistical areas (MSAs) and four combined statistical areas (CSAs). As of 2020, Philadelphia, the seventh-largest United States metropolitan area, is the state's largest metropolitan area followed by Pittsburgh and Allentown.
The U.S. State of Illinois currently has 47 statistical areas that have been delineated by the Office of Management and Budget (OMB). On July 21, 2023, the OMB delineated 14 combined statistical areas, 12 metropolitan statistical areas, and 21 micropolitan statistical areas in Illinois. As of 2023, the largest of these is the Chicago-Naperville, IL-IN-WI CSA, comprising the area around Illinois' largest city, Chicago.
The U.S. State of Mississippi currently has 27 statistical areas that have been delineated by the Office of Management and Budget (OMB). On July 21, 2023, the OMB delineated six combined statistical areas, four metropolitan statistical areas, and 17 micropolitan statistical areas in Mississippi. As of 2023, the most populous statistical area in the state is Jackson-Vicksburg-Brookhaven, MS CSA, comprising the metro area of its capital and largest city, Jackson.
The U.S. State of Arizona currently has 13 statistical areas that have been delineated by the Office of Management and Budget (OMB). On July 21, 2023, the OMB delineated two combined statistical areas, seven metropolitan statistical areas, and four micropolitan statistical areas in Arizona. As of 2023, the most populous of these is the Phoenix-Mesa, AZ Combined Statistical Area, encompassing the area around Arizona's capital and largest city, Phoenix.
The U.S. State of Alaska currently has four statistical areas that have been delineated by the Office of Management and Budget (OMB). On July 21, 2023, the OMB delineated two metropolitan statistical areas and two micropolitan statistical areas in Alaska. The most populous of these statistical areas is the Anchorage, AK Metropolitan Statistical Area, centered on the state's largest city of Anchorage.
The U.S. State of California currently has 42 statistical areas that have been delineated by the federal Office of Management and Budget (OMB).
The U.S. State of Alabama currently has 35 statistical areas that have been delineated by the Office of Management and Budget (OMB).
The U.S. State of Arkansas currently has 25 statistical areas that have been delineated by the Office of Management and Budget (OMB). On July 21, 2023, the OMB delineated four combined statistical areas, seven metropolitan statistical areas, and 14 micropolitan statistical areas in Arkansas. As of 2023, the most populous statistical area in the state is Little Rock-North Little Rock, AR CSA, comprising the metro area of its capital and largest city, Little Rock.
The U.S. State of Delaware currently has four statistical areas that have been delineated by the Office of Management and Budget (OMB). On July 21, 2023, the OMB delineated one combined statistical area, two metropolitan statistical areas, and one micropolitan statistical area in Delaware. As of 2023, the largest statistical area in the state is the Philadelphia-Reading-Camden, PA-NJ-DE-MD Combined Statistical Area, which includes Delaware's largest city, Wilmington.
The U.S. State of Florida currently has 35 statistical areas that have been delineated by the Office of Management and Budget (OMB). On July 21, 2023, the OMB delineated 7 combined statistical areas, 22 metropolitan statistical areas, and 6 micropolitan statistical areas in Florida. As of 2023, the largest of these is the Miami-Port St. Lucie-Fort Lauderdale, FL CSA, inclusive of the southeastern region of the state centered on Miami.
The Commonwealth of Puerto Rico currently has 13 statistical areas that have been delineated by the United States Office of Management and Budget (OMB). On July 21, 2023, the OMB delineated three combined statistical areas, six metropolitan statistical areas, and four micropolitan statistical areas in Puerto Rico. As of 2023, the largest of these is the San Juan-Bayamón, PR CSA, comprising the area around the municipality of San Juan, the capital and largest city of Puerto Rico.
The United States federal government defines and delineates the nation's metropolitan areas for statistical purposes, using a set of standard statistical area definitions. As of 2023, the U.S. Office of Management and Budget (OMB) defined and delineated 393 metropolitan statistical areas (MSAs) and 542 micropolitan statistical areas (μSAs) in the United States and Puerto Rico. Many of these 935 MSAs and μSAs are, in turn, components of larger combined statistical areas (CSAs) consisting of adjacent MSAs and μSAs that are linked by commuting ties; as of 2023, 582 metropolitan and micropolitan areas are components of the 184 defined CSAs.
