ATLANTA - Georgia voters cast more than 100,000 ballots before early voting ended Friday and while participation had been lower in some counties than two years ago, at least one had nearly tripled its early balloting by midweek.

Any voter can request a mail-in ballot or walk into a polling station starting 45 days before Election Day and cast a ballot. The state Legislature expanded the system two years ago so voters did not need a specific excuse - for example, out-of-town travel or an illness - to vote early.

"It started off slow but it's certainly picking up as we near the end of the early voting period," Secretary of State's Office spokesman Matt Carrothers said.

Early voters represent a small slice of Georgia's 4.9 million registered voters. As of Wednesday, the counties with the most early votes were also the state's most populous: Cobb, Fulton, Gwinnett, Dekalb and Chatham. By Wednesday, about 43 percent more voters had cast early ballots in Fulton than did so during the entire early voting period for the 2008 primary. But the number of early voters by Wednesday appeared down in Gwinnett Country and relatively flat in Hall County.

Comparing early voting trends is difficult since the nature of the elections and rules behind the system have changed markedly in the last few years. Two years ago, a presidential primary helped bring voters to the polls. And in 2006, voters needed an excuse to vote in person 45 days in advance - a rule that was changed by the Legislature in 2008.

Fulton's election director, Barry Garner, said he was surprised turnout hasn't been higher in the state's largest county. He expected between 10,000 and 15,000 people to have already cast ballots. As of Wednesday, just over 7,000 ballots were cast.

"I figured with the open seat for governor and the mood of the country, voters would be more energized," Garner said. "Maybe folks are waiting until Election Day to actually show up."

Garner said he estimated that total voter turnout in his country will hover around 25 percent, or roughly double what it was in 2008.

An uptick in early voting is under way in Chatham County, which contains Savannah. It's seen almost three times as many residents vote early by midweek than during the same period for the 2008 election.

To spur turnout, Chatham County has spread word about early voting using TV and radio broadcasters and in local newspapers, said Sandra Williams, director of Chatham County voter registration office. She said it also helps that the large number of candidates on this year's ballots are running their own early voting efforts.

"I'm thinking that now people are aware of early voting, and they like it," she said.

It remains unclear whether the increase in early voting in Chatham could help Savannah Republican Eric Johnson and whether relatively steady voting in Hall was an indicator for the campaign of Republican Nathan Deal, whose once represented the county in Congress. Both men are running for governor.

The early ballots will not be counted until Election Day.

"I think this year it would be very hard to read anything into the early voting patterns," said Alan Abramowitz, a professor of political science at Emory University who studies voting.

Candidates, however, view any vote as a good vote. And in a tight race, a few hundred votes could make the difference.

Congressman Tom Graves, who is running in the Republican primary, sent out a Twitter message Friday urging his supporters to vote early.

Getting die-hard supporters to the polls early will help Graves' campaign focus its Election Day get-out-the-vote efforts on undecided voters, said Tim Baker, Graves' campaign manager.

"It's important because I think it will grow through the years ... as more people find out how easy it is to do," Baker said.