RALEIGH, N.C. -- Nearly 75,000 people have already cast their ballots in North Carolina's presidential primary, even though the state's primary election day is nearly two weeks away.

The early votes have been cast under new rules that allow previously-unregistered voters to sign up and vote on the same day until May 3.

Both campaigns have launched efforts encouraging people to take part in the early voting. And polling sites have been flooded since they opened last week.

Voter registration is up overall, but the biggest spike is among blacks, who make up 20 percent of the state's registered voters. Those are positive numbers for Barack Obama, who has seen strong black support throughout the primaries.

Obama and Hillary Rodham Clinton are vying for the state's 115 delegates toward their Democratic White House bids