Election workers in Philadelphia have flagged thousands of provisional ballots that need ID verification.
Other counties have hundreds more.
LIVE TRACKER: Pennsylvania Mail-In Ballot Tracker
In order for your vote to be counted, you need to submit proof of identification to the board of elections.
The deadline for most options was 5 p.m. Tuesday, but you can still submit your form via email until 11:59 p.m.
For more information, visit this page at Phila.gov.
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And all of these votes in limbo matter because of how close the Pennsylvania Senate race is.
ABC has still not projected a winner, with Republican Dave McCormick ahead of incumbent Democratic Senator Bob Casey by about 35,000 votes.
McCormick has already declared victory, but Casey's campaign is not ready to concede before the final tally.
If the margin stays within half a percent, Pennsylvania law requires an automatic recount. That would have to be ordered by Thursday.
ELECTION RESULTS: Live election 2024 updates in the Philadelphia region and the focus on Pennsylvania