This map is called the Response Outreach Area Mapper. It fronts years of research and analysis of data that predicts of a household’s likelihood of answering the census. The distilled result is the Low Response Score, an estimate of the “non-return rate” based on a model that includes 25 factors.
The three most significant, in descending order:
Officially it’s called the P.L. 94-171 file, for Public Law 94-171, the 1975 law that defined and scheduled its release. You can see the proposed layout here. It’s commonly called the “redistricting file” because that’s its primary use, and state legislators are its primary customers. It will be released, state by state, between mid-February and late March in 2021.
The prototype of the Census 2020 file includes 297 columns of data. Rows represent geographical areas, including counties, cities, political districts, voting districts (precincts), tribal areas, census tracts, block groups and even census blocks, the smallest areas used in the census.
Most of the columns represent all 63 possible combinations of the official federal race categories for both Hispanic and non-Hispanic people. The same categories are repeated just for people 18 and older – the voting-age population. These make up the columns.
Also, new for Census 2020, the file will tally people living in group quarters – things like dorms, prisons and barracks. This is because some states, in drawing political districts, want to subtract or reallocate people in rural group quarters elsewhere.
Finally, there’s a simple breakdown of housing units, counting up how many are occupied and how many are vacant.