Counties and Equivalent Entities are primary legal divisions. In most states, these entities are termed “counties.” In Louisiana, these divisions are known as “parishes.” In Alaska, the equivalent entities are the organized boroughs, city and boroughs, and municipalities, and for the unorganized areas, census areas. The latter are delineated cooperatively for statistical purposes by the State of Alaska and the Census Bureau. In four states (Maryland, Missouri, Nevada, and Virginia), there are one or more incorporated places that are independent of any county organization and thus constitute primary divisions of their states. These incorporated places are known as independent cities and are treated as county equivalent entities for purposes of data presentation. The District of Columbia and Guam have no primary divisions and each area is considered a county equivalent entity for purposes of data presentation. The Census Bureau treats the following entities as equivalents of counties for purposes of data presentation: municipios in Puerto Rico, districts and islands in America Samoa, municipalities in the Commonwealth of the Northern Mariana Islands, and islands in the U.S. Virgin Islands. Each county or statistically equivalent entity is assigned a threedigit FIPS code that is unique within a state, as well as an eight-digit ANSI code.

The 2013 TIGER/Line Shapefiles are based on available governmental unit boundaries of the counties and equivalent entities as of January 1, 2013.

Detailed information about changes in the inventory and codes for county and equivalent areas can be found at: http://www.census.gov/geo/reference/county-changes.html

Core-based Statistical Area (CBSA) Codes – The 2013 county and equivalent entity shapefiles also contain fields with codes for combined statistical area, metropolitan or micropolitan statistical area, and metropolitan division. Counties form the building blocks for CBSAs.