County Longitudinal Template, 1840-1990

The County Longitudinal Template is a tool that enables researchers to allow for temporal changes in the geographic boundaries of counties in the United States. These data provide a decade-by-decade account of the administrative status of each county, starting in 1990 and tracing each census period back through 1840. The first four variables are the county name, ICPSR state code, FIPS code, and ICPSR county code. These four variables allow the researcher to select the counties for the state in question. The next 16 variables are ID variables for each census year, 1990 back to 1840. The last 13 variables are boundary change flags for each census year from 1960 to 1840.