A Combined Statistical Area (CSA) as defined by the U.S. Census Bureau is a aggregation of adjacent metropolitan and micropolitan statistical areas that are economically and socially interconnected. CSAs are used for providing a more comprehensive view of the larger regions in which residents live and work, transcending administrative boundaries to better illustrate the multi-faceted nature of these urban clusters.
A Micropolitan Statistical Area is a designation used by the U.S. Census Bureau to identify urban areas that have significant population centers with at least 10,000 but fewer than 50,000 inhabitants, often functioning as significant economic hubs within their region.
The designated city within a Metropolitan Statistical Area (MSA) or Micropolitan Statistical Area (µSA) that serves as the primary city or city center. This designation is used for demographic, economic, and planning purposes.
