Census tracts and tract codes - SCODEMeetup/kirwan GitHub Wiki
Census tracts are geographic entities within counties (or the statistical equivalent of counties). The entire area of a county is covered by census tracts, just as the entire area of a state is covered by counties and county equivalents. There are 74,134 tracts defined for the 2010 census in the U.S. and its territories.
Census tracts within a county are identified by a 4-digit basic code between 0001 and 9999, and may have a 2-digit suffix ranging from .01 to .98. The decimal point separating the 4-digit basic tract code from the 2-digit suffix is shown in U.S. Census Bureau printed reports and maps. However, in computer-readable files prepared by the Census Bureau and for files uploaded for FCC Form 477, the decimal point is implied and does not appear.
A census tract code may not be used more than once in a single county, but it may be used again in a different county in the same state or in a county in a different state. Therefore, a particular census tract within the nation must be identified by: its state, its county, and its tract code. One way this is done by the Census Bureau and by the FCC is to identify a particular tract using an 11-digit code consisting of a:
- 2-digit code for the state
- 3-digit code for the county (either of which may include one or more “leading” zeros)
- 6-digit code for the census tract (including any leading zeros, and also two “trailing” zeros in the many cases in which the basic tract code has no suffix)
Example: 39|049|009361
- 39 Ohio
- 049 Franklin County
- 009361 Tract 93.61