"The overwhelming trend over the last decade has been to expand early voting," said Wendy Weiser, director of the Democracy Program at the Brennan Center for Justice, which tracks voting legislation. "More states are adopting it and using it in their elections system, and voters are more likely to use it."
Following North Carolina, other states' voting will get underway later this month. Early voting in Iowa, where the race between Democratic Rep. Bruce Braley and state Sen. Joni Ernst is one of the most competitive on the map, begins Sept. 25 and runs through Election Day. Absentee ballots go out there, as well as in Georgia, in the second half of September.
And in some of these states, past early-voting rates have been higher than the national average. Take North Carolina, where ballots were mailed Friday: In 2012, more than 2.5 million voters, or about 56 percent of the state's electorate, voted early. In Iowa, just under 700,000 people—or 43 percent of voters—cast their votes early in 2012. In both Arkansas and Georgia, 44 percent of the total votes cast in 2012 were through early in-person voting. Colorado, where Democratic Sen. Mark Udall is in a competitive race, has switched over entirely to mail-in voting.
Early voting was key to President Obama's strategy in 2008 and 2012, focused on turning out minority voters who voted less frequently than their white counterparts. By locking down many of those votes ahead of Election Day, Obama's campaign was able to build in vote leads in key states such as Ohio and Colorado.
Weiser noted that there's been "a real increase" in the number of minority voters casting their ballots early—in some states, they did so at twice the rate of white voters.
The real challenge for Democrats is being able to turn what's been a presidential-year advantage into one that sticks even in a midterm year. In 2010, turnout among minorities, young people and lower-frequency voters dropped off significantly, resulting in the GOP wave that ushered in a new class of Republican governors, senators and representatives. If the electorate looks similar this year, a handful of Democratic incumbents in red states will have a tough time winning.
That's made more difficult by efforts to pass new voting restrictions in recent years, spearheaded primarily by GOP-led state legislatures, that have led to shorter early-voting periods in a handful of states that are key to the Senate map this year—namely North Carolina, Georgia, and West Virginia.
North Carolina has cut its early-voting program by a week, from 17 early voting days to just 10 this fall. The state Legislature also passed a strict voter-identification law, which does not go into effect until 2016.
Democratic Sen. Kay Hagan and her campaign have made voting rights an issue on the campaign trail, noting that the state's new, more restrictive voting laws were approved by GOP candidate Thom Tillis, who serves as the speaker of the state House. The campaign is also using a turnout operation that spokesman Chris Hayden called the "biggest North Carolina has ever seen for a Senate race" to help ensure that voters know what the new rules are and how to comply with them.