Spatially harmonized first-level geography
Harmonized first-level geography is available through a single global shapefile and individual country shapefiles applying to all countries in IPUMS. The shapefile corresponds to the variable GEOLEV1, which provides geographically stable first-level subnational units over time. IPUMS also provides harmonized migration variables where migration codes match corresponding harmonized first-level geography codes.
Changes over time in administrative boundaries are handled by combining the affected geographic units to create larger, temporally stable units comprised of two or more states, provinces, etc. Although most boundary changes involve the splitting of a larger unit into two or more smaller ones, other types of changes include the shifting of state or province boundaries.
The attribute data for the global file include codes for the GEOLEV1 variable, the BPLCOUNTRY (country of birth) variable, and the COUNTRY (country of residence) variable. The first three digits of GEOLEV1 give the country code, and the last three digits specify the first-level geographic unit within countries.
The table below lists the major unit of geography identified for each IPUMS-International country and provides GIS shapefiles for the sample years represented in the spatially harmonized geography and migration variables. Some countries (e.g. Chile and Poland) have two sets of spatially harmonized geography due to reorganization of administrative boundaries between the censuses.