Core-Based Statistical Area
A geographic region defined by the Office of Management and Budget (OMB) consisting of one or more counties anchored by an urban center of at least 10,000 people.
Core-Based Statistical Areas (CBSAs) are the primary framework the federal government uses to define metropolitan and micropolitan regions. A CBSA includes the core county (or counties) containing the urban center plus adjacent counties with strong commuting ties. CBSAs come in two flavors: Metropolitan Statistical Areas (MSAs, anchored by 50,000+ population centers) and Micropolitan Statistical Areas (anchored by 10,000-49,999 centers).
As of the 2020 Census-based delineations, there are 384 MSAs and 547 micropolitan areas in the United States. OMB revises CBSA boundaries after each decennial Census based on updated commuting patterns.
CBSAs are widely used in postal data to classify ZIP codes as metropolitan or micropolitan and to associate them with broader economic regions. Real estate, healthcare, and labor market analyses frequently rely on CBSA classifications.