In 2008 in North Carolina, 251,893 voters registered during one-stop early voting. That represented 5.8% of all voters. For context, about 60.6% of North Carolinians voted early in 2008.
These approximately 250 thousand registrations during one-stop early voting included 104,355 new voter registrations and 147,538 updated voter registrations.
I imputed a vote difference of 44,626 votes in favor of Obama solely from one-stop voters that registered to vote, or about 1.0% of the overall vote. Also, an estimated 6.9% of Obama's votes were cast by one-stop voters, and 4.8% of McCain's votes were cast by one-stop voters.