A Core Based Statistical Area is the official term for a functional region based around an urban center of at least 10,000 people, based on standards published by the Office of Management and Budget (OMB) in 2000. Areas defined on the basis of these standards applied with Census 2000 data were announced by OMB in June 2003. These standards are used to replace the definitions of metropolitan areas that were defined in 1990. The term "CBSA" refers to both metropolitan statistical areas and newly-created micropolitan areas collectively. Micro areas are based around Census Bureau-defined urban cluster of at least 10,000 and fewer than 50,000 people. The map located on the right shows the metropolitan areas (in red) and micropolitan areas (in blue) for the CBSAs for the United States and Puerto Rico (which is included in the US Census data).
