Michigan Secretary of State Terri Lynn Land estimates about 3.8 million voters across the state will turn out for Tuesday's election.
That's 52 percent of Michigan's 7.3 million registered voters and similar to the turnout in the 2006 gubernatorial election.
Detroit Clerk Janice Winfrey on Thursday estimated turnout at 25 to 30 percent of the city's 562,000 registered voters. She based her estimate on turnout in previous midterm elections.
Voters on Tuesday will decide races including governor, attorney general, secretary of state, the state Legislature and the Michigan Supreme Court along with many local issues.
About 5 million Michigan voters participated in the 2008 presidential election, or about 68 percent of registered voters.