###### OMB

Definitions

Metropolitan Statistical Areas (MSAs)

MSAs are defined by the Office of Management and Budget (OMB) and used by the Census Bureau and other federal government agencies for statistical purposes. 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 area. Such regions are neither legally incorporated as a city or town would be, nor are they legal administrative divisions like counties or separate entities such as states. As such, the precise definition of any given metropolitan area can vary with the source. A typical metropolitan area is centered on a single large city that wields substantial influence over the region (e.g., Chicago or Atlanta). However, some metropolitan areas contain more than one large city with no single municipality holding a substantially dominant position (e.g., Dallas–Fort Worth metroplex, Norfolk-Virginia Beach (Hampton Roads), Riverside–San Bernardino (Inland Empire) or Minneapolis–Saint Paul).

Primary Statistical Areas (PSAs)

A "primary" metropolitan area is defined as a metropolitan area that is not a component of a more extensive defined metropolitan area. The 574 primary statistical areas (PSAs) of the United States and Puerto Rico comprise all 169 Combined Statistical Areas (CSAs)[1] currently defined by the United States Office of Management and Budget (OMB) and the 405 of 929 Core Based Statistical Areas (CBSAs)[2][3]currently defined by the OMB that are not a component of a Combined Statistical Area.

On February 28, 2013, the United States Office of Management and Budget defined 1098 Statistical Areas for the United States and Puerto Rico, comprising 169 Combined Statistical Areas,[4] 388 Metropolitan Statistical Areas,[5] and 541 Micropolitan Statistical Areas[6] for the United States and Puerto Rico.[7] A total of 574 of these 1098 Statistical Areas qualify as primary statistical areas, including all 169 Combined Statistical Areas, 122 of the 388 Metropolitan Statistical Areas, and 283 of the 541 Micropolitan Statistical Areas. The OMB currently does not use the term "primary statistical area", but the term is commonly used to identify the most extensive OMB defined Statistical Area for a given county or county-equivalent

Combined Statistical Areas (CSAs)

A combined statistical area (CSA) is composed of adjacent metropolitan (MSA) and micropolitan statistical areas (µSA) in the United States and Puerto Rico that can demonstrate economic or social linkage. The United States Office of Management and Budget defines a CSA as consisting of various combinations of adjacent metropolitan and micropolitan areas with economic ties measured by commuting patterns. These areas that combine retain their own designations as metropolitan or micropolitan statistical areas within the larger combined statistical area.

The primary distinguishing factor between a CSA and an MSA is that the social and economic ties between the individual MSAs within a CSA are at lower levels than between the counties within an MSA.[1] CSAs represent multiple metropolitan or micropolitan areas that have an employment interchange of 25. CSAs often represent regions with overlapping labor and media markets. As of July 2012, there are 166 combined statistical areas in the United States, plus three in Puerto Rico

The United States Office of Management and Budget (OMB) has defined 917 core-based statistical areas (CBSAs) for the United States and 12 for Puerto Rico.[1] The OMB defines a core-based statistical area as one or more adjacent counties or county equivalents that have at least one urban core area of at least 10,000 population, plus adjacent territory that has a high degree of social and economic integration with the core as measured by commuting ties. The 929 Core Based Statistical Areas currently defined by the OMB include the 388 metropolitan statistical areas (MSAs),[2] which have an urban core population of at least 50,000, and the 541 Micropolitan statistical areas (μSAs),[3] which have an urban core population of at least 10,000 but less than 50,000

The United States Office of Management and Budget (OMB) has defined 382 Metropolitan Statistical Areas (MSAs) for the United States and seven for Puerto Rico.[1] The OMB defines a Metropolitan Statistical Area as one or more adjacent counties or county equivalents that have at least one urban core area of at least 50,000 population, plus adjacent territory that has a high degree of social and economic integration with the core as measured by commuting ties.

The United States Office of Management and Budget (OMB) has defined 535 Micropolitan Statistical Areas (μSAs) for the United States and five for Puerto Rico. The OMB defines a Micropolitan Statistical Area as one or more adjacent counties or county equivalents that have at least one urban core area of at least 10,000 population but less than 50,000, plus adjacent territory that has a high degree of social and economic integration with the core as measured by commuting ties.