Each candidate received five votes in Dixville Notch, New Hampshire, in the first tie in the hamlet's 50-year tradition as the first place to cast and count votes on election day, CNN reported on Tuesday.
US polling stations opened on Tuesday, with Democratic incumbent Obama and Republican challenger Romney locked in a tight presidential contest after a burst of last-minute campaigning.
Polls opened at 6am (11am GMT) in battleground states New Hampshire and Virginia – either of which could decide the election – as well as New York, New Jersey, Connecticut, Indiana, Kentucky, Maine and Vermont.
Opinion polls showed a close race nationwide too, with attention focusing on seven states where the outcome was a toss-up, one of them being the New England state of New Hampshire.
Both Romney and Obama urged their supporters to get friends and family to the polls as turnout could prove crucial to determining the winner.
"It just comes down to each of us as citizens," Obama said on Monday night in a voice hoarse from constant campaigning in the closing days of the campaign. "That's how our democracy is supposed to be."
He ended his campaigning in the toss-up state of Iowa, recalling his campaign four years ago that made him the first African-American president.
"When the cynics said we couldn't, you said, 'Yes we can'," he said as a few in the crowd shouted Obama's 2008 slogan with him.
Romney urged his supporters at an election eve rally to talk to undecided voters.
"Ask them to look beyond the speeches and the attacks and all the ads, and ask them to look at the record," he said in Manchester, New Hampshire. "Change was promised by the president, but change is not measured in speeches. It's measured in achievements."
Romney, who continued campaigning on Tuesday, ran down a list of election vows that he accused Obama of failing to fulfil. The president in 2008 "promised to do so very much, but he has fallen so very short", said Romney, a former Massachusetts governor who previously made a fortune as a private-equity investor.
"I've not only promised change, I have a record of achieving it," he said.
Obama also emphasised change in his rallies in a country suffering high unemployment and sluggish economic growth.
"When Americans come together determined to bring about change, we cannot be stopped," he said. "After all that we've been through together, we cannot give up now."
Regular voting is to begin Tuesday at 5am (10am GMT) when polls open in Vermont, which borders New Hampshire.
US states set their own polling hours, so polling centres would then open and close in waves across the four time zones of the continental United States. Montana, North Dakota, California and Idaho would be the final of the 48 continental states to vote, closing their polls at 4am GMT on Wednesday.
Further west, Hawaii finishes voting at 4am on Wednesday, followed by the last Alaska polls closing at 6am on Wednesday.
Dixville Notch, 30km south of the Canadian border, vies each year with Harts Location, 130km away and also in New Hampshire, for the honour of being the first place to vote in the presidential election.
Both open voting at midnight (5am GMT) with all their residents in attendance and close after the voters all cast ballots for an immediate hand count.
Obama held the advantage in Harts Location with 23 votes, compared with nine for Romney. &ndash Sapa-dpa