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WATERLOO, IA - SEPTEMBER 27: Voting booths are set up for early voting at the Black Hawk County Courthouse on September 27, 2012 in Waterloo, Iowa. Early voting starts today in Iowa where in the 2008 election 36 percent of voters cast an early ballot.  (Photo by Scott Olson/Getty Images)
WATERLOO, IA - SEPTEMBER 27: Voting booths are set up for early voting at the Black Hawk County Courthouse on September 27, 2012 in Waterloo, Iowa. Early voting starts today in Iowa where in the 2008 election 36 percent of voters cast an early ballot.  (Photo by Scott Olson/Getty Images)

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    Why early voting is a big deal

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Why early voting is a big deal

CNN's John King breaks down the swing states that will vote early and how some ballots will even be cast before the candidates debate.

Why early voting is a big deal

CNN's John King breaks down the swing states that will vote early and how some ballots will even be cast before the candidates debate.