Washington (CNN) -- Come the first Tuesday in November, when millions are streaming into polling stations across the country, as much as 40% of Americans will have already voted. In 2004, 22% of Americans voted early and that rate rose to 34% in 2008, according to Paul Gronke, Professor of Political Science who founded and runs the Early Voting Information Center at Reed College in Oregon. Not only is early voting changing the way Americans cast their ballot but it's also changing the way candidates run their campaigns. "People find it much easier if they can choose the time to vote ... rather than show up on one day of the week," said Tom Slockett, Johnson County, Iowa, commissioner of elections and the county's voting auditor.
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In 2004, 22% of Americans voted early and that rate rose to 34% in 2008
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Early voting has changed the times when voters hit the polls, and changed the way campaigns run
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While voters are taking advantage of early voting, impact on turnout is mixed and can cost governments more
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400,000 voters were disenfranchised in 2008 because they improperly filled out their absentee ballots
@placeholder begins early voting on September 27, almost a week before the first debate on October 3.