Hello, I am trying to track changes in occupational composition by ethnicity from 1970-2000 at the county level in NHGIS (using datasets 1970_Cnt4Pb, 1980_STF4Pb, 1990_STF4b, and 2000_SF4). However, the occupational breakdowns in each decade differ drastically. I know IPUMS USA has created a crosswalk for occupations (linked below), but the occupation definitions in NHGIS often do not match those in the crosswalk. Is there an NHGIS-specific crosswalk or some other way to get information on the occupation codes aggregated within each category in NHGIS?
You are correct that you can use the integrated industry (IND1950) and occupation (OCC1950) variables on IPUMS USA to crosswalk your NHGIS data to a consistent 1950 coding scheme. These variables leverage year-specific codes in OCC and INC and crosswalk them to a common scheme. For 2000, the dataset 2000 Census: EEO Worksite Data [Large Counties & Places] includes both Census occupation and industry codes that correspond to IND and OCC codes in IPUMS USA. For 1990, the dataset 1990 Census: STF 4b - Sample-Based Detailed Data with Race/Ethnicity Breakdown uses the 1990 census coding scheme.
Your starting point would be to create an extract with IPUMS USA census microdata from 1970-2000 with the variables IND, OCC, IND1950, and OCC1950. This blog post will then guide you through creating a crosswalk between the original IND/OCC code and the integrated variables. Note that you will need to create separate crosswalks for each of your sample years. Once you have your crosswalk, you can apply it to your NHGIS data to code all industry and occupation data to their corresponding IND1950/OCC1950 code.