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COUNTYFIP
County (FIPS code, identifiable counties only)

Description

IPUMS USA cannot identify most counties in recent samples.

COUNTYFIP identifies the county where the household was enumerated, using the Federal Information Processing Standard (FIPS) coding scheme.

COUNTYFIP codes are state-dependent; they must be combined with state codes (see STATEFIP or STATEICP) to distinguish counties located in different states.

Many county boundaries and some county names have changed over time. IPUMS does not impose a uniform county boundary system on the data, so each county listed for a given year in IPUMS should be assumed to have the boundaries that it had in that year.

Counties are not identified in public-use microdata from 1950 onwards, so IPUMS instead identifies counties, where possible, from other low-level geographic identifiers. These include State Economic Areas (SEA) in 1950; county groups in 1970 (CNTYGP97) and 1980 (CNTYGP98); and Public Use Microdata Areas (PUMA) from 1990 onwards, including Super-PUMAs (PUMASUPR) in 2000.

In 1950 and later samples, COUNTYFIP identifies a county if and only if:

  • it was coterminous with a single SEA, county group, or PUMA; or
  • it contained multiple SEAs, county groups, or PUMAs, none of which extended into other counties.
List of counties identified in 1950 and later samples:

For municipios, the Puerto Rican statistical equivalent of U.S. counties, see PRCOUNTA (alphabetic version) and PRCOUNTY (numeric version).

FIPS codes were first instituted around the time of the 1970 census, so historical counties that were dissolved before then have no FIPS code. COUNTYICP and COUNTYNHG supply codes for the complete history of U.S. county definitions. These alternative variables both use codes based on the 3-digit FIPS scheme with a fourth digit added to distinguish historical counties.

Like STATEFIP, COUNTYFIP facilitates merging IPUMS data with data from other sources that use FIPS codes.