Voters in New York, New Jersey, Maine, Connecticut, Virginia, Kentucky and Indiana were able to cast their ballots from 6:00 a.m. (11:00 GMT) - joining those of Vermont, where polls opened earlier. Polling stations opened 30 minutes later in the key state of Ohio, as well as North Carolina and West Virginia.
Two New Hampshire towns, Dixville Notch and Hart's Location, voted just after midnight, with Democratic candidate Barack Obama favored over his Republican rival John McCain by 15 votes to six in Dixville and 17 to 10 in Hart's Location, where two residents wrote in Ron Paul.
However, the opening of polling on election day has become largely symbolic this year, with around a third of voters estimated to have cast their ballots already.
Polls across the swing states of Virginia and Indiana will close by 7:00 p.m. (00:00 GMT Wednesday), with Ohio following half an hour later. If Sen. Obama wins any of those states, which all went for President George Bush in 2004, it is going to make it extremely difficult for Sen. McCain to win the election.
