Huh, just to throw another data point in here, I’m in Michigan and I vote by mail. (Well, by dropbox, but same difference). Our primary ballots this year were not separated into Democrats and Republicans. Both primaries appeared on the same ballot and there were big, clear instructions on the top stating to only vote in one primary. If you selected candidates in both primaries it would automatically void the ballot.
but you know better than that, don’t you? When they can create a t-bone shaped district to get rid of Cleaver, and no objection from courts, well