Codes and Frequencies
Most IPUMS data transformations are performed using variable harmonization tables that specify how each value in the source data is recoded. Some variables also require programming logic in addition to the harmonization table. The harmonization documents for this variable are:
GEO2_US identifies the consistent PUMAs (Consistent Public Use Microdata Areas). Each PUMA is an aggregation of one or more 2010 U.S. Census PUMAs (Public Use Microdata Areas) that, in combination, align closely (within a 1% population mismatch tolerance) with a corresponding set of 2000 PUMAs. PUMAs are effectively the smallest geographic units that can be consistently identified from the geographic codes available in U.S. Census PUMS from 2000 and later (until 2020 PUMAs take effect sometime after the 2020 Census). More details on construction of PUMAs can be found in IPUMS USA website.
A separate variable, GEO2ALT_US, identifies sets of 1980 county groups and 1990 and 2000 PUMAs that comprise comparable populations for samples from 1980 through 2011. GEO2ALT_US corresponds with CPUMA0010 variable in IPUMS USA .
GEO2_US is spatially harmonized to account for these boundary changes. Some detail is lost in harmonization; see the comparability discussion. A GIS map (in shapefile format), corresponding to GEO2_US can be downloaded from the GIS Boundary files page in the IPUMS International web site.
The full set of geography variables for the United States can be found in the IPUMS International Geography variables list. For cross-national geographic analysis on the first and second major administrative level refer to GEOLEV1, and GEOLEV2. More information on IPUMS-International geography can be found here.
Comparability — General
PUMAs and Consistent PUMAs
PUMAs are the smallest geographic units identified in U.S. Census Public Use Microdata Samples (PUMS) since 1990. PUMA definitions are altered after each decennial census, so PUMA codes are not consistently comparable across time.
To support spatio-temporal analysis of PUMS data, IPUMS defines consistent PUMAs as minimally aggregated sets of PUMAs that, when consolidated, align well across samples.
- All households
- United States: 2000, 2005, 2010, 2015