Minnesota doesn’t register by party, so you can’t be talking about Minn for “higher percentage of registered Dems” voted. About 29 states do register by party — I have not seen data showing that their turnout was unusually high, or higher than GOP. In a couple of states that I have seen published data, it wasn’t so. Do you have a source??
During the follow-up of the election process, I read information that led me to believe this was the highest percentage rate of Democrat voters to registered Democrat voters ever. If that’s not true, then I’ve been operating under a false assumption. I’ll nose around a bit and see what I come up with.