CHICAGO (WLS) -- Brandon Johnson will be the next mayor of Chicago. Paul Vallas told supporters Tuesday night he had called Johnson to concede.
While Vallas started the night with an early lead, the race quickly tightened to a 50-50 split. By 9:30 p.m. Johnson was leading Paul by more than 16,000 votes, a gap that has continued to widen and is expected to grow as mail-in ballots continue to be counted.
The Associated Press called the race for Johnson at about 9:35 p.m. Addressing his supporters a short time later, Vallas said the results showed the city was "deeply divided," but encouraged support for Johnson, who he said he had called to congratulate.
The Chicago Board of Elections said when polls closed 503,382 total ballots were cast, putting turnout at 33.2% of a total of 1,592,894 registered voters.
The mood inside Johnson's election night party was electric, buzzing with energy as supporters waited for him to come down and deliver his victory speech. And while funding from the Chicago Teachers Union, which Johnson was formerly an organizer for, and SEIU helped his campaign, he has all along credited his "multicultural, multi-generational movement" for carrying him from relative obscurity to the fifth floor of City Hall.
WATCH: Brandon Johnson's victory speech
In particular, he has touted his campaign's ground game, deploying people in the last five weeks to knock on doors, holding events, and sending text messages. He believes that beyond his message, it was his hard work that got him to this point.
In his victory speech, Johnson struck a triumphant and highly optimistic note. He talked about how tonight means the civil rights movement and labor rights movement have finally won, and said his government will be a government that truly belongs to the people of Chicago.
He also ended his speech saying this is a time to "celebrate the revival and the resurrection of the City of Chicago."
By contrast, Vallas' supporters were stunned and even booed when he told them he had conceded to Johnson, but the former CPS CEO and city budget director had clearly looked at the math and did not see a way for him to close the gap with the outstanding mail-in ballots.
WATCH: Paul Vallas addresses supporters
"It's critically, critically important that this campaign that I ran to bring this city together would not be a campaign that filled my ambitions if this election was going to divide us more," Vallas told his supporters. "So it's critically important we use this moment to come together, and have offered him my full support in his transition."
Chicagoans began lining up at the polls early Tuesday to make their choice count.
"I'm just happy to have the opportunity to vote," voter Rob Shapiro said. "I teach around the world and many places where people don't get to vote and I know how important this is."
Outgoing mayor Lori Lightfoot released a statement saying in part, "I congratulate Mayor-elect Brandon Johnson on his hard-fought runoff victory this evening. It is time for all of us as Chicagoans, regardless of our zip code or neighborhood, our race or ethnicity, the creator we worship, or who we love, to come together and recommit ourselves to uniting around our shared present and future."
Governor JB Pritzker also released a congratulatory statement, saying in part "I'd like to congratulate Mayor-elect Johnson on his victory. I am committed to a productive partnership that advances our shared priority of making Chicago an even better place to live, work, do business, and raise a family."
The voting super site in the Loop on Clark and Lake saw a surge during the morning rush.
Bill Rue said he had a hard time choosing between the two mayoral candidates, Brandon Johnson and Paul Vallas.
"I don't necessarily like either of them, because they both have negatives and positive, but it's very important to get out and vote," Rue said.
One of the biggest issues that drove people to the polls has been public safety and crime. Some say if there is no improvement, it could force them to leave the city.
"If it doesn't improve, I am really concerned about the safety of my family and my friends," voter Jonathan Soco said.
"One of the issues that's important to me would have to be the gun violence that's going on here, and the gang violence as well," said voter Elvira Garcia.
Craig Sims said the crime issue did not influence his vote.
"My concern is economic development on the South and West sides of the city," Sims said. "Not paying so much attention to the downtown area and what's happening up north but moving into the neighborhoods and taking care of the problems and fixing those."
Many voters said they did their homework, studying the candidates in the weeks leading up to Election Day.
"I watched a lot of the debates and a lot of mine was immigration, obviously, parents are immigrants, so that was a big one and then police also," voter Nubia Benitez said.
"Neither was my first choice, but I feel like even though neither one was, it still was very important for me to vote," Kristen Davis said.
William Lowry said his decision was easy.
"The Black vote is incredibly important," he said. "Oftentimes, where the Black vote goes often is where you see a lot of progress and a lot of change."
And some voters are just hoping for change, period.
"I hope for a breath of fresh air," said voter Asomah Akainyah. "I hope for someone who is going to really make their voice heard and advocate for the people, and the mothers, the family people, and really just a new horizon for Chicago."
It's not clear if we'll know who won the mayor's race by the end of the night. According to Chicago election officials, more people voted early and by mail.
It's not clear if we will know a winner by Tuesday night. Chicago takes mail-in ballots postmarked by Election Day and the number of ballots left to arrive have to be counted, and there are 91,000 mail-in ballots still outstanding.
Vallas' campaign strategist and other political observers believe it could take time to declare a winner.
"The only question is you know if that lead is three or four points, that's going to be hard to change. If that lead is less than a point, then we have to wait till every vote is counted," said Democratic strategist Tom Bowen.
To find your polling location, visit the Chicago Board of Elections website.