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 percent 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," said Democratic Gov. Kathleen Sebelius of Kansas, 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 particularly strongly for blacks and women.
Among the new voters in North Carolina is Shy Ector, 25, of Durham. She favored Massachusetts Sen. John Kerry 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. Barack Obama's candidacy was enough to make sure she did this year, she said.
"I was like 'Oh, now this is a reason to vote. This is different,'" Ector said. "I was inspired and I was excited."
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," Ector said of an Obama loss to Hillary Rodham Clinton. "I'm not going to say I'm just going to write off politics for good, but it does make you feel like you're doing all this work for nothing, and nothing's coming to fruition."
Even if some discouraged new 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 nominating process.
New voter registrations favored Democrats in North Carolina, which holds its primary Tuesday. 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 only doubled.
More than 49,558 unaffiliated voters signed up in the Tar Heel state, compared with just 16,858 in the first three months of 2004. The Democratic primary was the obvious draw, with 85 percent of unaffiliated voters who cast early ballots doing so on that ticket.
Cherie Poucher, director of elections in Wake County, home of the state capital of Raleigh, said registrations among the parties have historically kept pace with each other -- until this year. In the two weeks before the April 11 registration deadline, she said, the Democrats gained about 8,000 voters in Wake County while the GOP lost several hundred.
"We have never seen something like that before," Poucher said.
In Pennsylvania, where Clinton's victory in the April 22 primary kept her campaign alive, there were 40,000 more Republicans than Democrats in Bucks County in April 2004.
Among the new registrants in the first three months of this year, 6,537 signed up as Democrats while 2,200 did so as members of the GOP in the county north of Philadelphia. And 12,554 filed applications to switch to the Democratic Party. By the beginning of April, Bucks had become a Democratic county by a margin of nearly 4,000 registered voters.
"After January, they were just coming," said John Cordisco, the county's Democratic chairman.
Cordisco said party leaders had initially set a goal of turning the county blue by 2011. Then came the extended primary battle that gave Pennsylvania an important role. And while Clinton won Bucks County by a margin of 25 percentage points, accounts suggest that many of the new registrants are black voters inspired by Obama.
The overall figures on new registrations were compiled by the AP in a survey of election officials nationwide. Six states and the District of Columbia were unable to provide statistics, meaning the total number of voters who registered between roughly Jan. 1 and March 31 almost certainly exceeds 3.6 million. One of the six, North Dakota, does not require voters to register.
In the 21 states that were able to provide comparable figures from the first three months of 2004, only Iowa showed a decline. That state held its first-in-the-nation caucuses on Jan. 3.
The numbers even seem to be benefiting Democrats in states that generally lean Republican. In Wyoming, where registered Republicans still outnumber Democrats by more than 2-to-1, Democratic registrations in the first three months of the year surpassed those for the GOP. Ditto in West Virginia, Iowa, Louisiana and North Carolina -- all states won by President Bush in 2004. There could be more: Only 10 states had figures on new voter registrations by party.
Four states provided information about the race of registrants in both 2004 and 2008: Tennessee, Alabama, Louisiana and North Carolina. And in each, there was a surge in the registration of black voters. In North Carolina, more than 45,000 blacks signed up to vote in the first three months of 2008, compared with just over 11,000 in the first three months of 2004.
There was also a fourfold rise in black voter registrations in Alabama, while Louisiana and Tennessee saw increases of 64 and 17 percent.
Six states collected voter data by gender in 2008 and 2004, and the new-registration rate among women -- who have largely backed Clinton -- is up 89 percent in those states, compared with 74 percent for men.
Not all of the registrants are new to politics. A newly registered voter might be one who has moved to a new state. But the onslaught of registrations has overwhelmed election organizers, resulting in a mix of both excitement and anxiety as they prepare to count ballots cast by millions of new registrants.
North Carolina officials expect a turnout of around 50 percent in Tuesday's primary election -- double the rate of past primaries. Almost half a million voters cast early ballots, more than half the number who voted in the state's 2004 primary overall.
In Indiana, which also votes Tuesday, a flood of recent voter applications slowed election systems to a crawl and forced some counties to keep staff working around-the-clock to process the backlog.
In April alone, Hoosier election staffs processed 130,000 new or updated voter registrations. Many more people cast ballots in early voting.
"Those numbers completely obliterate any numbers from 2004," said Indiana Secretary of State Todd Rokita. For the primary, he said, "I've been pulling my staff in for war-game meetings, playing out every scenario. They're almost paramilitary tactics in terms of strategy."
David Woodard, a professor of political science at Clemson University who has advised Republican candidates, acknowledged the GOP is concerned about what appears to be a movement to voters to the Democratic Party attracted by Obama. But he noted that Ronald Reagan was supposed to lead the GOP to long-term political dominance but was never able to do so.
"These tides come in and wash in a personality," Woodard said. "But the tides of American politics are still pretty much the same, and the excitement of one candidate or one personality is not really long lasting."
It works both ways. In 1980, four years after Georgia Gov. Jimmy Carter swept the South on his way to the White House, the Democratic Party slipped and Republicans returned, largely dominating the region.
"People have had big impacts," said veteran Democratic strategist Bill Carrick. "But you also see that some things don't last that long."
And then there is the reality that registration numbers don't always add up to high turnout in November.
Historically, only a little more than 50 percent of voting-age adults cast ballots in U.S. presidential elections. By comparison, more than 70 percent of those in France and the United Kingdom go to the polls.
