The Supreme Court, in a 5-4 decision, upheld state laws that allow the counting of late-arriving mail-in ballots even if they were postmarked by Election Day.
Early voting is already underway in the midterm elections, though this year voters in some states are dealing with new laws governing how to cast ballots.
It's National Voter Registration Day. Here's how to register to vote in Pennsylvania, New Jersey and Delaware.
On Saturday, lawyer Michael Puppio, who is representing two candidates running for Delaware County Council, said a third-party vendor is responsible for the issues.
A printing error causes only one side of a mail-in ballot to print in Montgomery County. Officials say it impacts 16,000 ballots.
Tuesday is the deadline for Pennsylvania residents to apply for mail-in or absentee ballots in the upcoming primary election.