DURHAM, N.C. — Voter excitement, always up before a presidential election, is pushing registration through the roof so far this year — with more than 3.5 million people rushing to join in the historic balloting, according to an Associated Press survey that offers the first national snapshot.

Figures are up for blacks, women, and young people. Rural and city. South and North.

Overall, the AP found that nearly one in 65 adult Americans signed up to vote in just the first three months of the year. And in the 21 states that were able to provide comparable data, new registrations have soared about 64% from the same three months in the 2004 campaign.

Voters are flocking to the most open election in half a century, inspired to support the first female president, the first black, or the oldest ever elected.

Also, the bruising Democratic race has lasted longer than anyone expected, creating a burst of interest in states typically ignored in an election year.

Some Democratic Party leaders bemoan the long battle, with two strong candidates continuing to undercut each other. But there are clear signs that the registration boom is favoring their party, at least for now.

“This could change the face of American politics for decades to come,” Governor Kathleen Sebelius, a Democrat of Kansas, said, predicting permanent gains for her party. Republicans, concerned at least somewhat for 2008, say these surges come and go over the longer term.

While detailed data are available from only a handful of states, registration seems to be up strongly for blacks and women.

Among the new voters in North Carolina is Shy Ector, 25, of Durham. She favored Senator Kerry of Massachusetts while a student at the University of North Carolina at Chapel Hill four years ago, but never actually took the time to make sure she was registered to vote. Senator Obama’s candidacy was enough to make sure she did this year, she said.

New voters are generally less reliable. So there’s no guarantee this year’s newcomers will stick around in years to come — or even cast ballots in November if their candidate doesn’t make it.

“I will be very disappointed, and it will take me some time to recover,” Ms. Ector said of an Obama loss to Senator Clinton.

Even if some discouraged voters drop off, the numbers are striking.

Consider Pennsylvania and North Carolina — where the primary elections hadn’t been expected to matter because they occurred so late in the process.

New voter registrations favored Democrats in North Carolina, which holds its primary today. In the first three months of the year, the number of new Democratic registrants nearly tripled — to 74,590 — from those during the same period of 2004. New Republican registrations were up, too, but they doubled.