The United States Office of Management and Budget (OMB) defines micropolitan and metropolitan statistical areas. Metropolitan and micropolitan statistical areas consist of one or more counties (or county-equivalents). Currently defined metropolitan and micropolitan statistical areas are based on application of the 2000 standards (which appeared in the Federal Register on December 27 2000) to Census 2000 data, as updated by application of those standards to more recent Census Bureau population estimates. The current definition is as of December 2006.

If specified criteria are met, adjacent metropolitan and micropolitan statistical areas, in various combinations, may become the components of a new set of areas called combined statistical areas (CSAs). Using Census Bureau data the OMB compiles lists of CSAs. The areas that combine retain their own designations as metropolitan or micropolitan statistical areas within the larger combined statistical area. There are 126 CSAs defined by OMB as of December 2006.

Note that CSAs represent multiple metropolitan or micropolitan areas that have a moderate degree of employment interchange. CSAs often represent regions with overlapping labor and media markets.

See also

• Geography

• *Human geography

• **Demography

• United States

• *United States Census Bureau

• *United States 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)