Apologies for the somewhat off-topic question. Is there a source for PL94-171 redistricting data from the 2020 Census compiled by Zip Code Tabulation Areas?
I just tried to get ZCTAs from data.census.gov using the geos option and I get an error message.
And NHGIS offers Zip Code Tabulation Areas, but I don't see data for 2020 Census redistricting data there, either...
Block-to-ZCTA crosswalk time?
Yes, the 2020 Redistricting Data files included no data for ZCTAs. I suppose this is because the Bureau hasn't (or hadn't) yet defined the official 2020 version of ZCTAs and are waiting to release 2020 summaries for ZCTAs until that is done. (As I recall, ZCTAs are updated with each new decennial census.)I don't know of any source of a 2020-block-to-2010-ZCTA crosswalk. The block data records in the 2020 Redistricting Files don't include ZCTA codes, so that's not an option. Right now, the best way to achieve this may be with a spatial overlay of 2020 TIGER/Line files for blocks and ZCTAs.
BTW, another forum that's well suited for non-ACS census data questions (and I'm not saying it's wrong to pose a question like this here!) is the U.S. Census Bureau Slack channel: https://uscensusbureau.slack.com.
NHGIS has released crosswalks from 2020 blocks to 2010 blocks, so another way to go about this is to allocate 2020 block data to 2010 blocks, and then use a 2010 block-to-ZCTA crosswalk to summarize by 2010 ZCTA. You can get associations between 2010 blocks and ZCTAs from GeoCorr or from an NHGIS 2010 block-level table data file.