Early voting came to a close Thursday, with Chicago joining other areas around the nation in reporting record turnouts for the primary election.

By 11 a.m. on the last day of early voting in Chicago, 4,200 people had already voted, more than double the daily number in other early voting periods, according to the Chicago Board of Elections.

Thursday's high turnout matches record numbers reported over the entire 18-day early voting period. "We’re going to go way past 70,000," said Jim Allen, spokesman for the board. That would be three times as many early voters as in previous elections.

"Early voting has been very popular this primary season," said Paul Gronke, a professor at Reed College in Portland, Ore. and an early-voting expert. "Nearly every state that has early voting has reported a dramatic increase. And total turnout has been heavily Democratic."

According to Gronke, 35 states offer some form of early voting, by either allowing voters to cast absentee ballots without providing a reason or by allowing in-person advance voting.

Gronke said high turnout is unusual for a primary. Early voters are usually certain about their choice, he said, and in a primary, when the contest is between candidates of the same party, there tends to be less certainty than in a general election.

"We’ve been predicting record turnout for a long time," Allen said. "But it’s only now that people are starting to believe us."

The Chicago area has two prominent candidates -- Hillary Clinton and Barack Obama -- with strong ties to the region. But early voters have turned out in record numbers in states where there is not a native son in the running.

Among the 24 Super Tuesday states, Georgia reported more than twice the number of ballots were cast in the first three days of early voting than for the whole early voting period in the 2004 presidential primary.

"We attribute that to not only increased interest, because it’s a presidential election, but also because both of the parties' races are still highly contested," said Matt Carrothers, a spokesman for the Georgia secretary of state.

Brook Thompson, the state election coordinator in Tennessee, said they’ve also had more than double the number of early voters than in any other presidential primary, with 250,000 early voters. Thompson said the high turnout reflects intense interest in this election, but also Tennessee voters’ increasing familiarity with how to vote early. Tennessee has been offering early voting since 1996.

Gronke thinks the spike in early voting may reflect increased efforts on the part of the campaigns to get supporters to the ballot booth. "Early voting is a reality that campaigns have to deal with," he said. "And if they have the money it can be an advantage to them."

It’s not always an advantage for voters, though, because if their candidate of choice drops out of the race, those votes will be wasted. "There were probably some votes cast for Rudy Giuliani and John Edwards in Illinois," Gronke said.

In Utah, where early voting began in 2006 as in Chicago, there has not been the same surge in turnout. Joe Demma, the chief of staff for the lieutenant governor, said it’s not for lack of excitement. "We don’t necessarily have a dog in the fight as you guys do," he said. "But we do have [Mitt] Romney and he’s kind of a favorite son around here."

Romney is a former Massachusetts governor with strong ties to Utah and the Mormon Church based there.

"But what I think we’re seeing, as we see candidates drop out, people are waiting to cast their votes," Demma said.