The economic census provides data for the following types of statistical areas in the United States and Puerto Rico.
Metropolitan Statistical Areas have at least one urbanized area of 50,000 or more population, plus adjacent territory that has a high degree of social and economic integration with the core as measured by commuting ties.
Micropolitan Statistical Areas have at least one urban cluster of at least 10,000 but less than 50,000 population, plus adjacent territory that has a high degree of social and economic integration with the core as measured by commuting ties.
Metropolitan Divisions are subdivisions of Metropolitan Statistical Areas (into smaller groupings of counties) which include a single core with a population of 2.5 million or more.
Combined Statistical Areas are combinations of adjacent Metropolitan and/or Micropolitan Statistical Areas that retain their own designations as Metropolitan or Micropolitan Statistical Areas within the larger area.
These areas are defined in terms of whole counties (or equivalent entities) under the auspices of the OMB.
They are identified by a 3-digit ANSI Combined Statistical Area code (CSA), 5-digit ANSI Metropolitan and Micropolitan Statistical Area code (MSA) and 5-digit ANSI Metropolitan Division code (MD), which are sequenced alphabetically within each parent and component Metropolitan area.
Note: Metropolitan Area boundaries can change annually with changes in population and commuting patterns as documented in the American Community Survey, so the Metropolitan Areas published for the latest economic census may be different from those published previously.