Donald Trump has won the United States presidential election in a seismic upset that defied most pre-poll predictions and punditry, inflicting a loss that Hillary Clinton admitted was painful and would be “for some time”.

The president-elect, 70, swept aside his highly-fancied rival by claiming key states that pollsters had tipped would vote Democrat. Instead, Florida, Ohio, North Carolina, Iowa, Wisconsin and Pennsylvania went with Trump, handing him the 270 electoral votes he needed to take office.

Despite counts in some states continuing into early Wednesday morning (US east coast time), Mr Trump triumphantly addressed his “Victory Party” at the New York Hilton about 2.30 am local time to declare the win, announcing that Ms Clinton had called him to concede defeat.

“Now it’s time for America to bind the wounds of division,” the soon-to-be 45th president of the US told the crowd.

“We have to get together. To all Republicans and Democrats and independents across this nation, I say, it is time for us to come together as one united people.

“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.

“America will no longer settle for anything less than the best.

“I pledge to every citizen of our land that I will be president for all Americans and this is so important to me.”

Mr Trump, who’ll assume office in January, also promised to work closely with the international community to “seek common ground … not conflict”.

“I want to tell the world community that while we will always put America’s interests first, we will deal fairly with everyone. All people, and all other nations,” he said.

He’s keeping a list of enemies

However, later at the election night party a surrogate of Mr Trump and former contestant on his reality show The Apprentice, Omarosa Manigault, said the nominee was keeping a list of enemies.

Former reality TV contestant Omarosa Manigault. Photo: Getty

She was reacting to Republican Senator Lindsey Graham’s announcement on Twitter that he cast his vote for an independent candidate.

“It’s so great our enemies are making themselves clear so that when we get in to the White House, we know where we stand,” she said.

“If [Graham] felt his interests were with that candidate, God bless him. I would never judge anybody for exercising their right to and the freedom to choose who they want. But let me just tell you, Mr. Trump has a long memory and we’re keeping a list.”

Electoral College vote count

At the latest count the billionaire had won 276 of 538 US Electoral College votes compared to Ms Clinton’s 218, according to the US politics website, Politico.

A total of 270 votes is needed to win the presidency and some tipped Mr Trump to claim over 300 once counting is finished.

Donald Trump accepts the presidency:

Earlier, Ms Clinton chose not to address a huge crowd waiting for her in New York, preferring to send out her campaign chairman John Podesta instead. Her no-show was later criticised by some commentators.

Mr Podesta told the Democratic election-night party in New York the “election was too close to call”.

“They’re still counting votes and every vote should count. Several states are too close to call so we’re not going to have anymore to stay tonight,” Mr Podesta told crowds at around 2am US east coast time.

“Everybody should head home. You should get some sleep. We’ll have more to say tomorrow.”

But when Mr Trump appeared before his supporters less than an hour later, Ms Clinton had apparently conceded the election to him.

Ms Clinton eventually conceded publicly late morning Wednesday, telling her supporters just before midday they owed Mr Trump “an open mind and the chance to lead”.

She admitted the loss was tough to accept: “This is painful, and it will be for a long time,” she said.

She also expressed regret that she did not shatter the glass ceiling, but said, “Someday, someone will and hopefully sooner than we might think right now.”

Mr Trump and the defeated Ms Clinton had held their election night events in New York City just a couple of kilometres from each other. But the scenes could not have been more different.

A group of Ms Clinton’s supporters cry at her election night event in New York. Photo: AAP

Hordes of Ms Clinton’s supporters were in tears, while Mr Trump’s followers were sent into wild rapture after one of the biggest political upsets of all time.

Hours before the election The New York Times had given Ms Clinton more than an 85 per cent chance of winning the presidency. But early Wednesday afternoon (AEDT), after several hours of counting, they reversed their position, installing Mr Trump as favorite.

The Republican Party now hold the US Senate, House of Representatives and the presidency.

As the chances of Mr Trump winning soared about 1:15pm on Wednesday (AEDT), world money markets tumbled, including the US stock exchange and the Australian Stock Exchange (ASX).

Clinton’s campaign chairman John Podesta gave a bizarre speech before Mr Trump did.

The Dow Jones futures also dipped as much as 600 points in after-hours trading.

Australian Prime Minister Malcolm Turnbull sought to calm fears about a Trump administration just minutes after the former-reality television show host declared victory

“I understand that Australians have been confronted by the intensity of the political battle in the United States,” Mr Turnbull said. “Our relationship [Australia and the US] will continue to be strong, will continue to work together as we have done, with many presidents in years past to take on the challenges of our time.”

The result was unexpected given the nature of Mr Trump’s campaign and his lack of political experience. Throughout his campaign Mr Trump was enveloped by scandal, including constant accusations of sexism, racism and being disingenuous.

Mr Trump has never held public office. Ms Clinton has been involved in politics for more than 20 years, as a First Lady, Senator and, most recently, Secretary of State in the Obama administration.