The state of North Carolina maintains particularly good voter registration statistics. With their registration deadline having closed last week, let's take a quick look at the numbers.
Since the first of the year, Democrats have added about 250,000 voters to the Republicans' roughly 50,000, while unaffiliated voters also increased their numbers by about 170,000. What was a 10.6 point party ID gap at the start of the year is now 13.0 points. About half that gain came between the first of the year and the state's May primary, and the other half came between the primary and last week's deadline.
There is fairly close to a 1:1 correspondence between the party ID gap and the Obama-McCain gap, so these new registrations alone account for about one point's worth of the gains that Obama has made in North Carolina since the summer.
Meanwhile, about 150,000 black voters -- and 35,000 "other" voters -- have been added to the rolls since the start of the year. That compares with about 235,000 white voters.
Assuming that Obama captures 35 percent of white voters, 95 percent of black voters, and 60 percent of "other" voters, the change in the racial composition of the electorate since the first of the year is worth a net of about 1.5 points to Obama in his race against McCain.
EDIT: Also, some really good data mining on voter registration from Dr. Michael McDonald at George Mason University. Nearly half of newly-registered voters in Ohio are aged 18-29.