What happens if there is a tie in the 2024 US election between Kamala Harris and Donald Trump?

On Tuesday, Democrat Kamala Harris and Republican Donald Trump will face off in a US presidential vote that is shaping up as an extremely tight race for the White House. With 24 hours to go until most Americans go to the ballot box, no clear favorite has emerged in pre-Election Day polls.

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To win, Harris and Trump need to secure at least 270 of the 538 electoral votes up for grabs across the US‘s 50 states and the District of Columbia. (Find out more about how America’s Electoral College voting system works.)

But what happens if there’s a tie?

Given that Harris and Trump are neck and neck in the polls, experts are certainly not ruling out the possibility that the two chief candidates could end up with an even split of electoral votes. Were that to happen, it would fall to the members of the House of Representatives - the lower chamber of the US Congress - to vote for the president.

Held under the terms of the US constitution’s 12th Amendment, a so-called ‘contingent election’ sees each state back one candidate. “Representatives of states with two or more Representatives would therefore need to conduct an internal poll within their state delegation to decide which candidate would receive the state’s single vote,” the Congressional Research Service notes. A ‘contingent election’ should be held on January 6.

Has there ever been a tie in a US presidential election?

Yes, but only once - and it happened over two centuries ago. In 1800, Thomas Jefferson and Aaron Burr both received 73 electoral votes, before Jefferson was voted in as president by the House.

Just under a quarter of a century later, the lower chamber also decided the outcome of the 1824 election, John Quincy Adams defeating Andrew Jackson. On this occasion, however, a contingent election was required not because of a tie, but because no candidate secured a majority of electoral votes.