ICPSR County Codes: 1850-1930

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This page lists the codes used in the variable COUNTY, which employs the coding scheme of the Inter-University Consortium for Political and Social Research (ICPSR). The first 3 digits are identical to the FIPS county codes used in other datasets; ICPSR adds a digit to accommodate change over time (generally, if a county merged with another or was renamed before 1970, it receives a fourth digit of "5"). A full list of ICPSR County Codes can also be downloaded as an Excel file or as tab-delimited text.


County boundary files are available for the years listed below.
IPUMS data can be matched to these files using the STATEICP and COUNTY variables.

1850 Boundary Files 1860 Boundary Files 1870 Boundary Files
1880 Boundary Files 1900 Boundary Files 1910 Boundary Files
1920 Boundary Files 1930 Boundary Files