US Election 2024: When will we know if Kamala Harris or Donald Trump has won?

• When will we know the result of US election 2024?

• Americans vote on 5 November and counts begin immediately

• Will it be settled that night or drag on for weeks?

• Keep up to speed with the US Election in our live blog

The Betfair Exchange market on who will win the US presidential election on 5 November indicates that this could be one of the closest contests in American history.

Donald Trump and Kamala Harris know that every vote counts and who wins the White House could come down to the finest of margins.

At the time of writing Harris is the favourite, and has been since her TV debate victory on 10 September flipped the Betfair odds, to make Trump the outsider.

But the result may still be too close to call all the way until election day. The closer the result the longer it could take to determine who is the winner.

When will we know the result of the US election?

Usually we know the winner on the night of the election or the next day. To win the election one candidate needs to take 270 electoral college votes - find out how that works in this simple guide - and as soon as that has happened we know who is going to win.

Media outlets call each state for one of the candidates based on a projection of the votes counted so far and these calls are almost invariably accurate.

In 2016, enough states were called for Trump by 2:30am in Washington D.C. that he reached the required 270 and was declared the winner.

Four years later, the outcome was not so clear.

Result came three days after election in 2020

At the 2020 election, it was not possible to declare the winner for days. This was largely to do with the high number of postal votes and the reluctance of the Republicans to admit defeat.

Only hours after voting ended, Trump was already suggesting the election had been stolen from him, with no evidence at all to back up the claim.

The election took place on Tuesday 3 November 2020 but Joe Biden was not declared the winner until Saturday 7 November. This has lead some commentators to ask whether Trump will accept defeat in 2024 if Harris beats him.

Florida 2000, Bush v Gore and the hanging chads

Was 2020 the longest voters have ever had to wait to discover the result of a modern US election? No.

In 2000, George W. Bush and Al Gore fought what was then a bitter battle for the presidency. Bill Clinton, the Democractic president, had been in office for eight years, with Gore as his deputy, but the Republicans were determined to win back power.

The election took place on 7 November 2000 and, as the results came in, it was extremely close, with some coming down to margins of fewer than 400 votes. Eventually it all came down to Florida.

Initially, based on the exit polls (pollsters asking people who they voted for), it looked as if Gore had won Florida but, as counting began, Bush took the lead.

The state was counted and recounted. Eventually, the outcome hinged on what became know as "the hanging chads".

With the nation's eyes turned on Florida, news networks carried footage of scrutineers examining "hanging chads". This was the term given to small pieces of paper created when a hole was punched in a ballot on the voting machines that were used in Flordia then.

When some voters punched their ballots, the chad had not fully separated from the ballot, making their preference unclear. The hanging chads were discussed by teams of lawyers from both Bush and Gore campaigns and eventually the Supreme Court was asked to judge the outcome of the election.

After 36 days, on 13 December, the closest presidential contest in decades ended when a 5-4 vote by the Supreme Court judges said Bush was the winner. Finally, the American people had spoken. All nine of them.

Whatever happens on 5 November and beyond, Betting.Betfair is the place to stay up to date with US election predictions based on the latest odds.

What happens once the US election winner is declared?

The period after the election is the transition, if there is a change of president, as there will be after the 2024 US election.

It lasts for roughly two-and-a-half months. The new administration can use this time to appoint cabinet ministers and make plans for their term.

The president is officially sworn into office in January at their inauguration, which is held on the steps of the Capitol building in Washington DC.

Now read 2024 Presidential Election Betting: The latest data from the Betfair Exchange