Gina Nunez has never missed an election, primary or general, and found herself in the fellowship hall of a Methodist church in Phoenix today to vote before anyone else in her precinct. Before the sun came up, for that matter.

She is 43 years old and knows the routine. Still, she said she could not wait to vote this time. This time, she said, it felt somehow different, more exhilarating.

“It just feels like something new’s going to happen, something different’s going to happen with whoever we get,” Ms. Nunez, an elementary school curriculum coordinator who voted for Senator Obama in the Arizona Democratic primary, said.

Across the nation, voters like Ms. Nunez were taking part in, and in many cases marveling at, a political day like none in American history — a 24-state, coast-to-coast scramble of presidential primaries and caucuses.

In an already unusual election, the first in more than half a century without a sitting president or vice president on the ballot, it was the first time such a broad swath of voters had a say at the same time in determining the finalists.

In Alaska, people in the community of Fort Yukon were braving some of the worst conditions of the winter to gather at an early-evening caucus in the lobby of a radio station. Yesterday’s high temperature there: minus 54.

In Lower Manhattan, voters faced the prospect of fighting through throngs of euphoric New York Giants fans and a ticker-tape parade for the Super Bowl champions to cast ballots in the New York primary.

And in Meridian, Okla., dozens of voters drove down a red clay road in a light rain to the LeGrande family farm, where five voting booths were set up on an enclosed porch.

“I don’t have any griping rights if I don’t vote,” Carol Stephens said there.

With the race essentially down to two leaders in both the Republican and Democratic parties, voters also expressed wonder at the novelty of the field of candidates still standing.

On the Democratic side, there were a woman and a black man — Senator Clinton and Mr. Obama. For the Republicans, there were a Mormon and a 71-year-old former prisoner of war — Mitt Romney and Senator McCain.

In Chappaqua — Mrs. Clinton’s backyard — Stephen Piccininni said he voted for Mr. McCain because he had the most experience.

“McCain is able to say what has to be said,” he said. “He’s someone who knows the process and I think has the right solutions for Iraq and the economy. He’s the right guy for that.”

The Super Tuesday slate included primaries and caucuses in 21 states for the Republicans and 22 states for the Democrats. And at least one of them took place, in part, in a hot dog joint.

That would be Chicago’s U Lucky Dawg, which doubles as a polling place. Voters there were undeterred by both a technical glitch that left just one touch-screen machine working or the 6-foot frankfurter draped in an American flag that loomed nearby.

At the restaurant, a 52-year-old accountant who has served as an election judge since he was 18, David Turow, made note of what he called unprecedented voter enthusiasm.

“I just feel we live in this country, we should exercise our rights, you know?” he said. And as voters walked out, he said cheerily, “See you in November.”