"This victory belongs to the people of Cook County," Preckwinkle said. "Today, the people of Cook County have spoken with one voice."
Preckwinkle will be the Democratic nominee in the general election in November, defeating incumbant Todd Stroger and ending the Stroger family legacy that has held the post for more than a dozen years. With 86 percent of precincts reporting, Preckwinkle had nearly 50 percent. Stroger trailed among the four Democrats with about 13 percent.
""Life goes on. As I said, I know county government better than anybody in the room. That's because I spent all that time trying to make sure that it worked," Stroger said.
Todd Stroger was put on the ballot when his ailing father, John Stroger, retired.
Preckwinkle will be up against Republican Roger Keats in the general election come November. With 92 percent of the results in, he won his party's nomination with 68 percent of the vote.
"The beauty of it is, it sets up a clear race," Keats said. " 2010 should be a good year for Republicans, but I want to remind people that the Democrats run everything, city, county, state. How do you think it's going? Take a look at the options."
Four candidates compete for Democratic vote
On primary day, Democratic candidates for Cook County Board president voted and hoped others would follow their lead. Candidates were curious about what the weather's impact on the voter turnout would be.
"I encourage everybody in Cook County to come out and vote. I'm a history teacher by profession, and I know how important the right to vote is. And I encourage everybody to exercise that right to vote," said Ald. Preckwinkle, (D).
"We're going to work very hard today, and we're asking people to come out and vote in big numbers, prove the pundits wrong that people get discouraged just because they see a little bit of snow," said Dorothy Brown, (D) candidate for Cook County Board president.
"This is Democratic weather. We're very happy, feeling very good. We feel confident about people coming out to vote," said Terry O'Brien, (D) candidate for Cook County Board president.
Todd Stroger voted late in the day. He was one of three African-American candidates in the race. ABC7 spoke with some African-American voters about whether race impacted their vote.
"I don't think it's all about race. I think it's about most qualified individuals to get in there and do the job that's required," said Frederick Tucker, voter.
"I don't think it matters whether there's two or three African Americans on the ballot. I think people make a conscious effort to do their research on the candidate," said Isaac Cato, voter.
"I think the more the merrier, whether they are African American, no matter what ethnicity they are, I think it's great," said Michael Bernard, voter.
"I think it's too early to say that bloc voting is gone, but I think what you're seeing is that it starts to fracture when there are multiple options and multiple sources of dissatisfaction," said Richard Day,a political pollster and election consultant for ABC7. He says the dissatisfaction of voters and dissatisfaction within the Democratic Party may have more influence on the election than the diversity of candidates.
"It's hard to imagine that you've got an incumbent Democrat as president of Cook County Board, and the Cook County Democratic Organization endorses no one. It's fascinating," said Day.
Two GOP candidates seek Cook Co. Board presidency
There were two candidates seeking the Republican nomination for Cook County Board president.
Keats cast his vote Tuesday morning in north suburban Wilmette. Keats' current job is a financial advisor.
His challenger, Chicago Police Lieutenant John Garrido III, cast an early ballot, so he was not at a polling place Tuesday morning.