The knife-edge US presidential election will come down to a handful of key battleground states, but it could be days or even weeks before a winner is declared.
The 2020 vote will have a nail-biter conclusion - and appears to be heading to the Supreme Court - with the race between Republican President Donald Trump and Democratic challenger Joe Biden too close to call on Wednesday morning.
The result now hinges on the so-called "blue wall" states of Michigan, Wisconsin and Pennsylvania that flipped and sent Trump, 74, to the White House in 2016, plus tight races in Arizona, Georgia, Nevada and North Carolina.
Mr Trump falsely claimed victory and declared the election "a major fraud", while Mr Biden, 77, said he was "on track to win this election". But the results are incomplete, with millions of ballots still to be counted, and no candidate can credibly claim victory.
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Both candidates were still short of the 270 electoral votes need to win.
Mr Trump won the battlegrounds of Florida, Ohio and Texas, dashing Mr Biden's hopes for a decisive early defeat of the president.
Mr Biden, the vice president under former president Barack Obama, was projected to win Arizona, the first major flip of the night, and was eyeing the Rust Belt battlegrounds of Michigan, Wisconsin and Pennsylvania for possible breakthroughs once those states finish counting votes cast earlier by mail and in person.
Winning those three states would be enough to give Mr Biden, 77, an Electoral College victory.
But even without winning Pennsylvania, victories in Arizona, Michigan and Wisconsin would put Mr Biden in the White House as long as he holds the states that Mr Trump lost to opponent Hillary Clinton in 2016.
These are the states that will determine the next president of the United States.
Due to a surge in mail voting amid the coronavirus pandemic - as well as the states' varying rules for when ballots can be counted - the final results for all the states are expected to take days to be revealed.
Pennsylvania
2016 winner: Trump (+0.7 per cent)
Electoral votes: 20
Pennsylvania traditionally leans Democratic is part of the so-called "blue wall", but it narrowly flipped to Mr Trump in the 2016 vote.
It is a must-win for Trump if he is to get another four years in the Oval Office, and the results could end up in the courts.
Mr Trump held a slight lead in the opinion polls heading into Tuesday's vote.
The counting of mail-in ballots will run into Wednesday and possibly even later.
Last week, the US Supreme Court let stand a ruling by Pennsylvania's top court that officials in the state could accept mail-in ballots three days after Tuesday's election, so long as they were postmarked by Election Day.
Mr Trump has vowed to launch a court fight to try to stop the state from counting mailed ballots that are received in the three days after the election.
The president voted by mail despite his criticism of the practice.
Michigan
2016 winner: Trump (+0.23 per cent)
Electoral votes: 16
Like Pennsylvania, Mr Trump narrowly won Michigan, another "blue wall" state, four years ago.
Wisconsin
2016 winner: Trump (+0.8 per cent)
Electoral votes: 10
Wisconsin also leans Democratic, and the opinion poll average gave Mr Biden a lead of almost seven per cent leading up to the election.
Arizona
2016 winner: Trump (+3.6 per cent)
Electoral votes: 11
It appears Arizona will swing back to the Democrats, with Mr Biden being the projected winner.
The state was considered a toss-up heading into the election and it was one of the Democrats' top targets.
Georgia
2016 winner: Trump (+5.0 per cent)
Electoral votes: 16
Georgia leans Republican and it was expected to be narrowly held by Trump.
North Carolina
2016 winner: Trump (+3.6 per cent)
Electoral votes: 15
North Carolina was expected to be another toss-up on election day, with polls in the state flipping repeatedly between the two candidates.
In a blow to Trump, the Supreme Court declined last week to block the state's plan to tally ballots that are postmarked by Tuesday and arrive by November 12.
Nevada
2016 winner: Clinton (+1.4 per cent)
Electoral votes: 6
Opinion polls gave Mr Biden a slight lead in Nevada before the election.
The counting of mail-in ballots could go on for days, as the state sent ballots to every registered voter this year and those ballots only have to be postmarked by November 3.
