"Unprecedented" voter turnout for the US presidential election is reported in several key states.
Election Day turnout is expected to reach records in several states. There have been massive campaign efforts to register new voters.
Democrat Barack Obama is seeking to become the country's first black president while Republican John McCain is attempting to defy the opinion polls.
Virginia's secretary of state Jean Jensen said up to 40% of the state's registered voters had cast their ballots by 10am on Tuesday.
Virginia usually votes Republican, but has been under assault by the Democrats.
A a massive voter response is reported in Missouri, a bellwether state which has voted for the presidential winner in every election since 1904 with only one exception.
In Ohio, statewide voter turnout of 80% is expected according to the secretary of state's office.
The BBC reports 130 million Americans are expected to vote. Long lines of voters are reported at many locations, in addition to the 29 million who have voted early.
Senator Obama, 47, cast his ballot in Chicago. He later went to Indiana for one last campaign appearance.
His running mate Senator Joseph Biden voted in Wilmington, Delaware.
Senator McCain, 72, was in Arizona, his home state, to vote. His running-mate Sarah Palin voted in her hometown of Wasilla, Alaska.
Senator Hillary Clinton said on Tuesday there would be "a big win" for the Illinois senator. She was speaking outside a polling station in Chappaqua, New York.
In the first voting of the day, Senator Obama won by 15 votes to six in Dixville Notch, New Hampshire. Voting there began at midnight, with a 100% turnout.
It was the first time the village had voted for a Democrat since 1968.
House & Senate seats
There are also elections for the entire US House of Representatives and a third of US Senate seats. Democrats are expected to expand majorities in both chambers.
They need to gain nine Senate seats to reach a 60-seat majority that would give them extra legislative power.
A total of 270 votes in the Electoral College is needed to win the White House.
Opinion polls indicate Senator Obama is ahead in enough states to give him the win.
However, results in Florida, Indiana, Missouri, North Carolina, Virginia, Pennsylvania, Nevada and Ohio are expected to be crucial to the outcome.
