"It's about right on track with 2008," Von Nida said.

In St. Clair County, with 164,000 registered voters, more than 16,000 people have voted early, with another 7,000 mail-in absentees, said Bob Delaney, the St. Clair County clerk.

The high number of early and absentee voters stems from the fact that many people have found early voting more and more convenient since the law governing this procedure was changed in 2006, Delaney said.

"It's coming along really good and a lot of people are really taking advantage of it," Delaney said.

Under state law, Illinois county clerks and election boards can't begin counting early and absentee ballots until the paper ballots from their respective precincts have been turned the night of Election Day.

For Delaney, the counting of the early and absentee ballots is relatively straightforward. That's because those votes are recorded on memory cards that resemble credit cards, Delaney said.

"So we can't do anything with the early voting or the absentees until all the election judges in the 144 polling places are in," he said. "If everything goes good it could be 10 o'clock" for final results to be tabulated.

At about 3:30 p.m. on Election day, Democratic and Republican monitors will assemble to watch as election judges open large envelopes containing mail-in absentee ballots. The judges must determine that signatures on the absentee applications match the ballots.

"The judges put everything back in the envelopes, sign off on it and we put them in a box that we don't count" until the corresponding precinct ballot boxes are brought in, Delaney said.

If balloting runs late Tuesday night, it won't be because of early or absentee voting, Delaney said.

"It's when they screw around in the precincts not getting their stuff up there," he said. "So we can't do anything with the early voting or the absentees until all the election judges in the 144 polling places are in."

The polls Tuesday open at 6 a.m. and close at 7 p.m. At stake is the race for president of the United States, Congress, a number of state and county races and referendums.