The deadline to apply was 5 p.m.
Read More: Voter Guide 2024 for Pennsylvania, New Jersey and Delaware
Action News was at the Delaware County Voter Services Center in Media where people were waiting for about two hours.
While the application could have been done online, some people in line were hoping to vote on demand. In other words, they wanted to apply for their ballot, receive it, fill it out, and return it - all in one trip.
"It's almost like April 15th for taxes. People are coming in asking for ballots at the very last minute," said Jim Allen, Delaware County's director of elections.
Part of the hold-up: mail-in ballots are a bit more complicated than voting on Election Day.
"Did it include the secrecy envelope? Was it signed? Was it dated? Was it signed in the right place?" Allen said. "It's not like self-checkout at the Wawa, you know? It's a little more complicated than that."
Action News was also at City Hall in Philadelphia, where some people waited for hours to register for a mail-in ballot.
Line wraps around City Hall on last day to apply for mail-in ballot in Pa.
Chopper 6 video showed the line wrapped around the building.
But volunteers with "Party to the Polls" helped make the wait more bearable with pizza, water and even candy!
Officials want to remind voters who got mail-in or absentee ballots that they must be turned in by 8 p.m. on Election Day.
If you missed the deadline, and are unable to vote in person on Election Day, you can still apply for an emergency absentee ballot at PA.gov.