I’d like to analyze demographic and employment data from IPUMS USA based on census tract. Do I need to use NHGIS data if I’m interested in census tract geographic data? Ultimately, I’d like to merge this data with the FARS dataset from the USDA which bases observations using census tract.
The most granular geography identifier available in the ACS Public Use Microdata available via IPUMS USA is the Public Use Microdata Area (PUMA), which must contain at least 100,000 residents at the time of the corresponding census in order to protect respondents’ identities. While other geographic units are inferred in recent years (e.g., county, city, metro) and explicitly reported in some historical data (e.g., enumeration district), no geography variables smaller than PUMA are independently identified prior to 1990. To analyze data on the census tract level with publicly available data, you will need to access summary tables on IPUMS NHGIS. Based on your description of FARS data being available at the tract-level, it should be relatively straightforward to merge NHGIS estimates onto these data; the primary reason to use IPUMS USA instead of NHGIS is if the specific summary statistics you are interested in are not available in the published estimates.
Yes, makes sense - thank you!