Democratic presidential candidate Hillary Clinton will win Maryland, the District of Columbia, Rhode Island, Illinois, Delaware, Massachusetts and Connecticut, major US broadcasters project.

Similar projections late Tuesday say Republican nominee Donald Trump will win Tennessee, Mississippi, Oklahoma.

Added to states called in the previous hour, the early results give Clinton a combined 75 votes from eight states and the District of Columbia in the electoral college. Trump, who has captured seven states, has 57 electoral votes.

Each state's electoral college value is weighted by population. A candidate needs 270 to clinch the White House.

Among the hard-fought swing states that will decide the presidential race is Florida, where both candidates were running neck-and-neck.

Polls have also already closed in New Hampshire and Pennsylvania, but the races remains too close to call. North Carolina, Ohio and Virginia closed earlier but are also yet to be decided.

Colorado, Michigan, Wisconsin and Arizona are due to begin counting at 0200 GMT.