The Marshall Project extracted the number of adults in correctional facilities per county from the 2000, 2010 and 2020 Decennial Census.
This data was used for the story There Are Fewer People Behind Bars Now Than 10 Years Ago. Will It Last? by Weihua Li, Jamiles Lartey, and David Eads.
According to the Census Bureau's definition, "correctional facilities" include federal detention centers like immigration detention centers, federal and state prisons, local jails, correctional residential facilities like halfway houses, and military jails.
The file includes these fields:
state: State postal codes.county: County name.FIPS: 6-digit FIPS code for the county.total_population_20: Total population of the county in the 2020 Census.incarcerated_20: Number of incarcerated people in correctional facilities as of the 2020 Census.total_population_10: Total population of the county in the 2010 Census.incarcerated_10: Number of incarcerated people in correctional facilities as of the 2010 Census.total_population_00: Total population of the county in the 2000 Census.incarcerated_00: Number of incarcerated people in correctional facilities as of the 2000 Census.