Hollydolly, we have had early voting for those who prefer it, for a long time now. It used to be because of convenience, people were going to be traveling or otherwise unavailable on Election Day, etc. This year, the coronavirus comes into it as well. Many of the usual polls (such as schools and community centers) are closed. There are alternative polling places set up, but many of them are far away from where people live, or people just don't know where they are. And people are worried about spending hours in long lines. So voting early by mail or drop box is becoming more and more attractive.
According to today's paper, the early voters favor Biden 2 to 1. The Trump supporters hope they will catch up on Election Day. Many of the early voters said they wanted to get their votes recorded as a statement against the "status quo." Can't go any further discussing that aspect of it. But I probably can say this: as JimBob said, it's very much along partisan lines. We seem to have become two nations. I wonder when somebody is just going to name this "Civil War II."