Core Based Statistical Area (CBSA) Definitions
March 4, 2019
Metropolitan Statistical Areas (MSAs), Combined Statistical Areas (CSAs), Micropolitan Statistical Areas (MICROs), and Metropolitan Divisions (MDIVs) in the Woods & Poole database are as defined in the July 2015, Office of Management and Budget (OMB BULLETIN NO. 15-01), Revised Delineations of Metropolitan Statistical Areas, Micropolitan Statistical Areas, and Combined Statistical Areas, and Guidance on Uses of the Delineations of These Areas.
All Woods & Poole historical data back to 1969 are revised to reflect the new 2015 OMB Metropolitan Area (MSA, CSA, MICRO, and MDIV) definitions. There are 382 MSAs, 171 CSAs, 551 MICROs, and 31 MDIVs in the 2019 Woods & Poole database.
New England City and Town Areas (NECTAs) and Combined New England City and Town Areas (CNECTAs) are not in the Woods & Poole database because they are defined with geographic units smaller than counties. The 19 MSAs, CSAs, and MICROs in Puerto Rico are also not included in the Woods & Poole database.
All Core Based Statistical Areas (CBSAs) are included in the Woods & Poole database. CBSAs are MSAs or MICROs; CBSA is a collective term for both of these geographies. There are 933 CBSAs in the Woods & Poole database, based on the 2015 OMB definitions.
MSAs, as defined by the OMB, 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 — a new set of 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. The central cities that form the basis on MSAs and MICROs are generally included in their titles, as well as the name of each state into which the MSA or MICRO extends. MSAs and MICROs are defined in terms of whole counties (or equivalent entities), including in the six New England States. If the specified criteria are met, a MSA containing a single core with a population of 2.5 million or more may be subdivided to form smaller groupings of counties referred to as Metropolitan Divisions. MDIVs are not comparable to either MSAs or MICROs and should not be ranked together.
According to the OMB if specified criteria are met, adjacent MSAs and MICROs, in various combinations, may become the components of a new set of areas called Combined Statistical Areas (CSA). For instance, a CSA may comprise two or more MSAs, a MSA and a MICRO, two or more MICROs, or multiple MSAs and MICROs. In the Woods & Poole database CSAs are defined in terms of counties. According to the OMB combinations for adjacent areas with an employment interchange of 25 or more are automatic. Combinations for adjacent areas with an employment interchange of at least 15 but less than 25 are based on local opinion as expressed through the Congressional delegations.