Madison's mayor urged all residents to get out and vote on Tuesday.
"This is a very different election and all these polls, which are based on projections of likely voters, may well be wrong, because it looks like the likely voter pool has changed," said Paul Soglin.
Lines were long at the city clerk's office on Friday, where the city issued nearly 17,000 absentee ballots.
More than 9,000 voted absentee at the clerk's office.
"A lot of the voters that are registering, we're finding they haven't voted since the year 2000. And we don't ask them, 'why are you choosing to register now?' We're just happy to get people registered and facilitate the right to vote," said Maribeth Witzel-Behl.
Witzel-Behl is still waiting for nearly 2,300 absentee ballots to be mailed in.
The clerk's office must receive them by 4 p.m. on Friday, June 8, to be counted in this election.
That means that if Tuesday's races are close, the results may not be official for about a week, until all of the mailed-in votes can be tallied.
A reminder that voters on Tuesday do not need to bring ID to the polls. The state's voter ID law is still under injunction. For voters planning to register to vote at the polls, all that is needed is proof of residence, officials said.