Random ballots can be tossed out because of a law almost as old as the state itself. It happens from time to time in Wisconsin -- and almost nowhere else.

By Thursday, all absentee ballots for those across Wisconsin who have already requested them will have been sent out.

An absentee ballot in Wisconsin gets returned with an error, like the voter failing to sign the envelope, but it mistakenly gets counted anyway, because a municipal election worker initially didn't catch the error when taking the ballot out of the envelope.

Voting begins today in Wisconsin – one of several battleground states likely to decide the election's outcome.