The Wisconsin Elections Commission said at least 590 people cast provisional ballots in last week's election because they didn't have a photo ID.
The commission says the number of provisional ballots could increase as more clerks turn in their reports. The provisional ballots allow someone who doesn't present a photo ID to have their vote count when they return with the proper identification by the Friday following Election Day.
It was the first presidential election in Wisconsin where voters were required to show photo IDs at the polls. Some Democratic lawmakers said they believed the law is flawed and would jeopardize the ability of some people to vote.
Turnout for the presidential election in Wisconsin was about 66 percent of the voting age population, based on unofficial results.