The indomitable Nate Silver at fivethiryeight.com analyzes some of the early voting patterns. There is a lot of good news for Republicans and a little good news for the Democrats.
The most significant thing that jumps out at me, however, is the wide divergence from state to state. The GOP number in Pennsylvania and Florida are really strong, and the Democratic numbers in West Virginia are almost unbelievable. So much of the attention in political commentary is focused on the national level, but there are 435 distinct congressional races this year and 37 distinct senatorial contests.
Early voting is in indication of an effective Get-Out-the-Vote effort, and GOTV decides close elections.
It will be interesting to see if these early voting numbers change in the course of the week. We may have a pretty good idea of what the final results will look like in some contests before election day.