Definition
COUNTYUS identifies the household's county of enumeration using the Inter-University Consortium for Political and Social Research (ICPSR) coding scheme. Counties are assigned codes alphabetically within states. The first 3 digits are identical to the FIPS county codes used in other datasets; ICPSR adds a digit to the FIPS codes to accommodate change over time. COUNTY allows the IPUMS-USA and IPUMS International pre-1950 data to be easily merged with ICPSR data. The variable also identifies areas that were not part of any county, including the independent cities of Virginia and some Indian lands.
For more information, see "ICPSR County Codes" on the IPUMS-USA website.
COUNTY is a state-dependent variable; it must be read in combination with the State variable (last two digits of GEO1_US) to distinguish between counties located in different states.
Note that many county boundaries and some county names changed over time. We have not attempted to impose a uniform county boundary system on the data, so a particular county listed for a particular year should be assumed to have the boundaries that it had in that year. GIS boundary files can be obtained from the IPUMS NHGIS site.
COUNTYUS is completely compatible with the IPUMS-USA variable COUNTY.
