29 states allow mail-in ballots postmarked by Election Day sent from overseas to be counted days after an election. A case before the Supreme Court could take that decision away from the states. 

The Conversation
Americans have had their mail-in ballots counted after Election Day for generations − a Supreme Court ruling could end the practice
29 states allow mail-in ballots postmarked by Election Day to be counted days after an election. A case before the Supreme Court could take that de...