Close race in US election according to early results

Republican White House nominee Donald Trump could clinch key states Indiana and West Virginia, but Florida looks as if it could go to Democrat Hillary Clinton.

She could also take the northeastern state of Vermont, in the first results of Tuesday's US presidential election, television networks projected.

It was still too early to determine a winner in three of the first six states to close their polls - Republican-leaning South Carolina and Georgia.

The first states closing voting stations at midnight UK time were Georgia, Kentucky, Vermont, Indiana, South Carolina and Virginia.

Hours earlier, Trump made a last-minute appeal to voters to turn out, saying the election was "far from over".

"Don't let up, keep getting out to vote - this election is FAR FROM OVER! We are doing well but there is much time left. GO FLORIDA!" he tweeted.

Millions of Americans turned out on Tuesday to decide whether to send Clinton to the White House as their first woman president or to put their trust in maverick populist Trump.

"Hillary, she has a history," said Charmaine Smith, 50, an African-American retail manager as she cast her ballot in Harlem. "All Trump has is the bullying."

But R. Raju, a 70-year Indian immigrant from Staten Island, New York, cast a confident vote for the Republican and his promise to reclaim power from a corrupt Washington elite.

"Trump would be a great president," he said. "Not good, great. He's like a Ronald Reagan."

Trump has refused to say whether he would accept the election's results, citing with no evidence the possibility of a rigged outcome.

His statement threatened to undermine a fundamental pillar of US democracy and raised the prospect that his fervent supporters would not view Clinton as a legitimate president if she won.

Asked on Tuesday in an interview with Fox News if he would accept the election results, Trump continued to demur, saying "We're going to see how things play out."

In a sign that Trump is preparing a legal challenge, his attorneys filed suit in Nevada alleging that the Clark County registrar of voters kept early voting stations open hours beyond the designated closing time.

According to the preliminary exit polls, most Americans who voted had at least a moderate amount of confidence that election ballots would be counted accurately.