The outcome of the US presidential election is on a knife edge, with Donald Trump so far doing much better than the pollsters predicted.
Both Mr Trump and his Democratic challenger Joe Biden are running neck and neck in a number of swing states.
The president is projected to have held the must-win state of Florida – a major boost to his re-election bid.
But Mr Biden could snatch Arizona, a once reliably conservative state. The vote caps a long and bitter race.
Other key states such as Georgia, Pennsylvania, Wisconsin, Michigan and North Carolina are toss-ups.
With the nation on edge, the final result may not be known for days as postal votes are tallied.
More than 100 million people cast their ballots in early voting before election day on Tuesday – setting US on course for its highest turnout in a century.
Control of Congress is also at stake. As well as the White House, Republicans are vying to hang on to a Senate majority.
Republicans have lost a Senate seat in Colorado, but gained one in Alabama.
Mitch McConnell, the Republican Senate leader, and Trump ally Lindsey Graham have both been re-elected.
The House of Representatives is expected to stay in Democratic hands.
What are the presidential results so far?
With partial results in, Mr Biden has a solid lead in Arizona. Fox News has projected Mr Biden will win that state and CBS News, the BBC’s US partner, said it was leaning the Democrat’s way.
But the Trump campaign said it was too early to declare a winner in Arizona. A loss for Mr Trump in that once reliably Republican state would be a potentially serious setback.
Another sunbelt state, Texas, is leaning Mr Trump’s way, projects CBS News. Fox has forecast that Mr Trump will win the Lone Star state.
The battlegrounds in the Midwest and Rust Belt of Pennsylvania, Michigan, Iowa and Wisconsin look as though they could go either way.
Pennsylvania, along with Florida, is considered a must-win for Mr Trump if he is to stave off defeat.
Cliffhanger counts are also under way in two more critical swing states on the East Coast, Georgia and North Carolina.
No surprises have emerged yet in the other states.
Mr Trump will keep hold of Ohio and Missouri, known as bellwether states because they have so often predicted the eventual winner, according to the BBC’s projection.
The BBC also projects Mr Trump will win Florida, Alabama, Mississippi, Idaho, Wyoming, South Carolina, Kansas, Nebraska, Utah, Louisiana, Indiana, North Dakota, South Dakota, Kentucky, Tennessee, Oklahoma, Arkansas and West Virginia, all as expected.
Mr Biden will retain his home state of Delaware, along with California, Virginia, New York, Oregon, Washington, Illinois, New Hampshire, Connecticut, New Mexico, Colorado, Vermont, Maryland, Massachusetts, New Jersey and Washington DC, according to BBC projections.
CBS projects Montana is leaning Mr Trump’s way, while Minnesota, Nevada, Maine, Hawaii and Rhode Island were trending towards Mr Biden.
Mr Trump narrowly lost Minnesota in 2016 and his campaign is hoping to pick it up this time.
Voting ended on the US West Coast at 23:00 EST (04:00 GMT on Wednesday).
National opinion polls gave a firm lead to Mr Biden, but pointed to a closer race in the handful of states that are likely to decide the outcome.
Projections are based on a mixture of exit poll data and, in most cases, actual votes counted – and are only made where there is a high degree of certainty.
In the US election, voters decide state-level contests rather than an overall, single, national one.
A desert oasis for Biden?
While many of the in-play sun belt states – Florida, Georgia and Texas – appear to be disappointments for Joe Biden, Arizona is offering a ray of hope. The Democrat posted a substantial lead as early votes were quickly tabulated in the state, and he could be on his way to making it the first to switch sides from the 2016 results.
If Biden does prevail in the border state, his path to the presidency becomes less daunting.
Instead of having to win all three “blue wall” states (Michigan, Wisconsin and Pennsylvania) that Hillary Clinton lost, he would only have to flip two of them (plus winning an electoral college vote in Nebraska or all of Maine, if he loses Pennsylvania).
Donald Trump publicly feuded with Arizona’s favourite son John McCain prior to the senator’s death in 2018, and his widow, Cindy McCain, endorsed Biden earlier this year.
Although the president held several rallies in Arizona in the past week, it appears the trends that have been moving the desert state toward the Democrats in recent years will deliver an important boost to Mr Biden on what is shaping up to be a long night.
What does the exit poll data show?
An exit poll conducted by Edison Research and published by Reuters suggests that four out of 10 voters nationally think the handling of the coronavirus pandemic in the US is “going very badly”.
A third of voters cited the economy as the issue that most concerned them, according to the poll.
Exit poll data also suggest Mr Biden had the edge with women voters by 57% to 42%, with black voters (87% to 11%), with under-29 year olds (64% to 33%) and among voters with or without a college degree.
Mr Trump appeared to hold the advantage with over 65 year olds (51% to 48%).