(CNN) - Early voting gets underway in Arizona Thursday. The state becomes the tenth in the nation where early or state-wide absentee voting is underway in the November 2 midterm elections.
Vermont kicked it off back on Sept. 20, followed by South Dakota on Sept. 21, Iowa and Wyoming on Sept. 23, Nebraska on Sept. 27, Ohio on September 28, Wisconsin on October 3, and California and Indiana on Oct. 4.
Early voting gets underway in another 17 states and the District of Columbia over the next two weeks.
In 2008, there were 27 states where at least a quarter of the voters cast their ballots before Election Day, either through absentee voting or early voting. And there were 11 states where more than half of voters cast their ballots before election day.
As early voting has exploded over the past few election cycles, it's changed the game for both voters and campaign strategists.
"Early voting has grown in popularity, with more voters in more states casting ballots before Election Day. It's really changed the decision calculus behind elections for both candidates and voters. It can be a double-edged sword," says CNN Political Research Director Robert Yoon.
"For the campaigns, if someone casts an early ballot for you, it's like money in the bank. But if they vote against you, that's a lost vote that no amount of TV ads or baby-kissing can change. For voters, you just have to hope that the candidate you voted for back in September is still the candidate you want on November 2nd," Yoon also said.
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