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COUNTYICP
County (ICPSR code, identifiable counties only)
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Description

IPUMS USA cannot identify most counties in recent samples.

COUNTYICP identifies the county where the household was enumerated, using the Inter-University Consortium for Political and Social Research (ICPSR) coding scheme.

COUNTYICP codes are state-dependent; they must be combined with state codes (see STATEICP or STATEFIP) 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.

All counties are identified in 1850 to 1950 full count files. Counties are not identified in public-use microdata samples from 1950 onwards, so IPUMS instead identifies counties, where possible, from other low-level geographic identifiers. These include State Economic Areas (SEA) in the 1950 1% sample; county groups in 1970 samples (CNTYGP97) and 1980 samples (CNTYGP98); and Public Use Microdata Areas (PUMA) from 1990 onwards, including Super-PUMAs (PUMASUPR) in 2000.

In 1950 and later samples (excluding the 1950 full count), COUNTYICP 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).

ICPSR county codes are generally ordered alphabetically by county name within states. With a few exceptions, ICPSR codes correspond to 3-digit FIPS codes (as identified by COUNTYFIP) followed by an added zero digit. The fourth digit is used to accommodate the complete history of U.S. County definitions. FIPS codes were instituted around the time of the 1970 census, and historical counties that were dissolved before then have no FIPS code. For such counties, ICPSR generally appends a fourth digit of 5.

Like STATEICP, COUNTYICP facilitates merging IPUMS data with ICPSR data. COUNTYICP also identifies areas that were not part of any county, including the independent cities of Virginia and some Indian lands.

In multi-year ACS/PRCS samples that span different PUMA definitions, this variable is based on whichever PUMA definition is associated with the respondent's survey year (as given by MULTYEAR). This occurs only in the 2022 5-year samples and in multi-year samples that include both 2011 and 2012 survey years. For more information about how PUMA definitions vary within multi-year samples, see the PUMA variable description.