I am using the NHGIS crosswalk for block group part data (1990 to 2010). As noted in the readme, the bgp1990gj variable depends on more geographic units than just state-county-tract-block group. However, when I download 1990 data at the blck_grp_598 level (such as …ds120_1990_blck_grp), many of these geographic units are not in the data (for example, county subdivisions are missing). This makes it impossible to do a one-to-many merge between the 1990 blck_grp_598 data and the crosswalk file. Moreover, some of the weight variables differ by 1990 state-county-tract-block group, so I am hesitant to just drop duplicate rows.
Could you please advise on (a) where to find the extra variables so that I can construct bgp1990gj in the population tables or (b) what I’m missing? Thanks!