Micropolitan areas are geographic entities defined by the Office of Management and Budget (OMB) using published standards that are applied to Census Bureau  data. Micropolitan areas were first defined in the 2000 OMB standards and are a differentiation of nonmetropolitan counties into two distinct groups: micropolitan and nonmicropolitan.

A micropolitan statistical area is a nonmetropolitan county or group of contiguous nonmetropolitan counties that contains an urban cluster of 10,000 to 49,999 persons. A micropolitan statistical area may include surrounding counties if there are strong economic ties between the counties, based on commuting patterns.   Nonmetropolitan counties that are not classified as part of a micropolitan statistical area are considered nonmicropolitan.