Combined Statistical Area
Combined statistical area (CSA) is a term for a combination of nearby metropolitan (MSA) and micropolitan statistical areas (µSA) across the 50 US states and the territory of Puerto Rico that can demonstrate economic or social links. The OMB 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.