HARRISBURG — Two Pennsylvania counties had to replace poll books at all polling places in the middle of in-person voting during Tuesday’s election because of what officials described as mistakes made in creating the voter data.

Affected voters deciding local races and whether to give three Democratic justices another term on the state Supreme Court were offered provisional ballots as a temporary fix. Officials said no races were affected and that few voters left polling places without voting.

Chester County — the state’s seventh-most populated county that’s part of Philadelphia's heavily populated suburbs in southeastern Pennsylvania — got a judge’s order to extend voting by provisional ballot for two hours past the usual closing time of 8 p.m.

Chester County apparently used voter data containing only voters registered with the two major parties — like it might for a primary election — for the printed poll books, Secretary of State Al Schmidt said Tuesday night.

Poll books contain a list of registered voters and their addresses that election workers at each polling place use to determine who can vote there and to check off who has voted.

By mid-afternoon, the state and county supplied supplemental poll books with some 75,000 third-party and unaffiliated voters who were omitted from the original books, Schmidt said. There will be a formal review of what happened, the county said.

In Fayette County, officials discovered the Department of State mistakenly had supplied electronic voter data from the 2024 voter file, officials said. The Department of State called it “human error,” but otherwise didn’t say how it would prevent the error in the future.

Voters arriving at the polls, in some cases, found that the county’s electronic poll books listed them as having already voted.

Election workers were instructed to switch to backup paper poll books that the county had created with accurate voter data, county election director Marybeth Kuznik said.