A
combined statistical area (
CSA) is composed of adjacent
metropolitan (MSA) and
micropolitan statistical areas (µSA) in the
United States and
Puerto Rico that can demonstrate economic or social linkage. 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.