Hi, we are hoping to use a 2010-2020 tract geographic crosswalk (built from the block crosswalk) in order to avoid going down to the block-level every time we transform data across census vintages. Is there a pre-existing crosswalk at the tract-level on the NHGIS website that I’m missing?
If not, would this be an appropriate way to transform block weights to the tract-level?
Multiply 2010 block population by WEIGHT to get partial block population counts. Sum partial block population counts up to the tract level (grouping by 2010 and 2020 tracts) to get partial tract population counts. Divide these partial counts by the 2010 tract population to get WEIGHT_TRACT.
We’ve begun work on tract-to-tract crosswalks and aim to release them in a few weeks, hopefully by the end of August.
Until then, yes, the method you describe is a good way to generate a tract-to-tract crosswalk. We’ll essentially use that same method for our crosswalk, doing the same thing with block counts of housing units & households, etc., in addition to population, in order to produce various interpolation weights.
That said, as explained on our crosswalks page, we recommend starting from smaller units than tracts if possible. If you start with tract data, it often requires disaggregating from large tracts to smaller tracts and tract parts; if you start from smaller units, you can avoid much of that disaggregation and the errors that come with it. E.g., if there’s data on your characteristics of interest for block groups, you could use our crosswalk from 2010 block groups to 2020 tracts to get more accurate standardized tract data than if you start with 2010 tract data.