(CBS News) Election Day is seven weeks away, but before Nov. 6, around 44 million people are likely to have already cast their votes.
Early voting, which starts in South Dakota and Idaho today, has grown more common with each presidential election over the last 12 years. It's a shift that makes voting more convenient, accessible and gives early indicators as to which side has an edge when it comes to enthusiasm and turnout efforts. Early voting only boosts overall voter turnout marginally, but in states like Ohio and Florida -- where lawsuits over early voting are pending -- a marginal boost in turnout could make all the difference.
In-person early voting opens today in South Dakota and in some counties in Idaho, though ballots are already coming in from a handful of other states: Kentucky, Indiana and the battleground states of North Carolina and Wisconsin.
In those four states, voters can already submit absentee or mail-in ballots. However, for a more accurate understanding of when the campaigns can drive voters to the ballot box en masse, CBS News considers early voting to start when a state has opened drop-off centers for ballots or in-person voting sites.
Since 2002, after the passage of the Help America Vote Act, many states adopted rules allowing large numbers of people to vote before Election Day. Currently, 34 states (including 10 battleground states) plus the District of Columbia offer early voting.
Just 16 percent of votes in the 2000 election were cast early, but that figure rose to 22 percent in 2004 and 33 percent in 2008. This year, the CBS News polling unit predicts at least one third of ballots -- or around 44 million -- will be cast before Election Day, though that figure could reach as high as 40 percent. In battleground states, early votes could account for anywhere from an estimated 5 percent of the vote (as in Pennsylvania) to an estimated 80 percent (in Colorado).
According to Paul Gronke, director of the Early Voting Information Center at Reed College in Portland, Ore., "People who vote early are people who've made their minds up."