Voter turnout on Tuesday was higher than in the two previous Chicago elections, but the increase was modest given the absence of an incumbent in the mayor’s race for the first time in 22 years. Forty-two percent of registered voters cast ballots, compared with 33 percent in 2007 and 34 percent in 2003.

“Everyone’s an expert about why people don’t come out to vote, and no one knows for sure,” said professor Paul Green of Roosevelt University. He thought the key Tuesday was the lack of suspense in the mayor’s race. “People get excited when there is competition. I give Emanuel a lot of credit. He ran as an incumbent even though he wasn’t one.”