Core Based Statistical Area Reference Maps Metropolitan areas are reviewed and possibly redefined after each decennial Census. In 2003 the US Office of Management and Budget established Core Based Statistical Areas (CBSA). CBSAs can be a: Metropolitan Statistical Areas (MeSAs) built around a population core of 50,000 or more Micropolitan Statistical Area (MiSA) created around a population core of 10,000 to 50,000 Combined Statistical Area combining adjacent Metropolitan or Micropolitan areas. The 2013 areas were defined by the US Office of Management and Budget on February 28, 2013. The 2003 areas were defined on June 6, 2003. See the US Census Bureau for information on on current, proposed, and historical CBSA designations. A list and maps of North Carolina micropolitan, metropolitan, and combined statistical areas (and other regions) can be found on LINC.