Donald Trump will become the 45th US president after a stunning victory over Democrat Hillary Clinton.
The Republican nominee defied pre-election polling to claim swing states, winning the key battlegrounds of Florida, Ohio and Pennsylvania.
He told cheering supporters that Americans must now unite and “bind the wounds of division”, after a gruelling, acrimonious campaign.
Global markets plummeted, with the US dollar diving and gold prices surging.
As poll counting went late into the night, it was Mr Trump’s shock victory in Wisconsin that put him over the 270 out of 538 electoral college votes needed to win the White House.
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The US president-elect took to the stage with his family at his victory rally in a New York hotel ballroom and said: “I just received a call from Secretary Clinton. She congratulated us on our victory.
“Hillary has worked very long and very hard over a long period of time, and we owe her a major debt of gratitude for her service to our country.”
He added: “It is time for us to come together as one united people.”
The real estate tycoon, former reality TV star and political newcomer, who was universally ridiculed when he declared his candidacy in June last year, said his victory had been “tough”.
‘Popular revolution’: By Anthony Zurcher, BBC News, Washington
Donald Trump defied all expectations from the very start of his presidential campaign more than a year ago.
Very few people thought he would actually run. He did. They thought he wouldn’t climb in the polls. He did. They said he wouldn’t win any primaries. He did. They said he could never overcome resistance from the Republican establishment and win his party’s nomination. He did.
Finally, they said there was no way he could compete for, let alone win, a general election matchup with Hillary Clinton. Now he’s President-elect Trump.
He staged the most unconventional of campaigns, running on gut instinct and his trademark bombast when others – both within his own party and outside – counselled moderation and a pivot to positions perceived to be more acceptable to mainstream voters.
He stayed true to the methods and tactics that got him to the cusp of the presidency, and in the end he was rewarded for it.
Down the stretch Mr Trump boasted that he was leading a movement, riding the crest of a popular revolution that would change the face of American politics. He was right.
Mr Trump has so far won 28 US states, smashing into Mrs Clinton’s vaunted electoral firewall in Pennsylvania and Wisconsin, states that have not supported a Republican presidential candidate since 1988 and 1984 respectively.
He also prevailed in Iowa, which has not elected a Republican since 2004.
Mr Trump held on to solidly Republican territory, including in Georgia, Arizona and Utah, where the Clinton campaign had invested resources in the hope of flipping the states.
Mr Trump, 70, will take office in January with a Republican-dominated Congress, as Democrats were unable to wrest control of the Senate in Tuesday’s general election.
Mrs Clinton, 69, has only notched up victories in 18 US states and the District of Columbia.
New Hampshire and Michigan – which had also been expected to fall in the Clinton column – remained too close to call as of Wednesday morning.
There has been no public comment from the Democratic candidate, who dreamed of becoming the first female US president. She did not appear at what was meant to be her victory rally in Manhattan.
Around the world, international leaders have begun congratulating Donald Trump on his election upset.
Russian President Vladimir Putin – for whom Mr Trump has voiced support – said he hoped US-Russia ties could be improved from their current “critical condition”.
European Commission President Jean-Claude Juncker said close co-operation was needed to deal with “unprecedented challenges” around the world.
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In other developments:
- As the result became clear, crowds outside the White House broke out into spontaneous protests while Trump supporters cheered
- Massachusetts, Nevada and California voted to legalise recreational marijuana, which could lead to the creation of the largest market for marijuana products in the US
Nationwide exit polls underscored America’s stark divide. Male voters were much more likely to back Mr Trump, while women backed Mrs Clinton by a double-digit margin.
Nearly nine in 10 black voters and two-thirds of Latinos voted for the Democrat, but more than half of white voters backed the Republican.
Mr Trump, a populist billionaire, provoked controversy on the campaign trail for comments about women, Muslims and a plan to build a wall along the US-Mexican border.
He fired up white, working-class American voters who were angry at the Washington establishment and felt left behind by globalisation.
On the eve of the vote, Mrs Clinton was ahead by four points in a BBC aggregate of opinion polls, but it was well within the margin of error.
She saw her campaign dogged by FBI investigations into whether she abused state secrets by operating a private email server during her time as US secretary of state.
Last Sunday, the law enforcement bureau cleared her once again of any criminality.
Mr Trump and Mrs Clinton were vying to succeed Democratic President Barack Obama.
After two four-year terms in the White House, he was barred by the US constitution from running for re-election.