I see this come up a lot in discussions about voting in America. Postal votes disproportionately go to Democrats, hence the Democrats want to expand postal voting while Republicans want to restrict it (and insist there is totally a bunch of fraud going on).
I’ve googled with a few search engines and haven’t found a convincing reason. Lots of evidence that the skew is real, but no explanation as to why. Indeed, if one just looks at demographics, one would expect postal voting to benefit Republicans by facilitating votes from people in the countryside who live far away from voting centers.
So what actually gives?
It’s just covid, before covid mail votes were proportional, then voting by mail was encouraged to avoid spreading covid. That made the number of Democrats voting by mail go up and the number of Republicans go down out of spite. Republican politicians just followed the reflex of Republican voters to resent prosocial behavior and tried to make use of it.