US election day 2024: when will we know who won?

But major questions remain about the timing of the results, who is voting, concerns over misinformation, and even fears of potential political violence. Both campaigns are also bracing for a prolonged legal fight, which could further complicate the election outcome.

How long will it take to know the winner?

Vote counting will continue beyond election night, and the final outcome of the presidential race will take time. Even in states that count their ballots relatively quickly, a close race could delay the projection of a winner by days.

The size of the map and the tightness of the race make it hard to predict when a winner could be declared. Each state has its own ballot-counting rules and potential legal challenges that can delay results.

In 2020, the Associated Press declared Joe Biden the winner four days after polls closed, on Saturday afternoon. However, The AP didn’t call North Carolina for Trump until 10 days after Election Day, and Georgia for Biden 16 days later following hand recounts.

Both campaigns view the race as exceptionally tight across key swing states likely to determine the outcome — Arizona, Georgia, Michigan, Nevada, North Carolina, Pennsylvania, and Wisconsin — barring any major surprises.

Of the key swing states, Pennsylvania is likely to take longer than election night, while Wisconsin is presumed to finish most counting on Wednesday. Arizona and Nevada could take days.

But the truth is no one knows when the race will be called.

Polls first begin to close on the East Coast around 10 p.m. UK time, when results will first start coming in. The rest will trickle in overnight until polls close on the West Coast at 4 a.m. GMT.

Who has voted so far?

More than 78 million Americans have already cast their votes as of Monday, according to the University of Florida’s Election Lab — 42,665,195 in-person and 35,357,535 mail ballots.

The total number of votes cast is already almost half the 160 million votes returned in 2020, the highest turnout the US has seen in more than a century. Overall, however, many experts predict turnout to be slightly lower than in 2020.

A key reason for the increase is that Trump has urged his supporters to vote early this time — a shift from 2020, when he encouraged Republicans to vote in person on Election Day. Early voting numbers show that millions of Republicans have followed his advice in recent weeks.

The critical question is whether the surge in early voting by Republicans will ultimately reduce the number who turn out on election day.

There are also changes among Democrats. Four years ago, amid the pandemic, Democrats largely voted early. This time, without the public health concerns, more Democrats are expected to vote in person on election day.

Going into election day, it is up to the campaigns to identify which voters they still need to mobilise for Tuesday. In this regard, many experts say Democrats could have an edge.

Trump’s campaign and the Republican National Committee have outsourced much of their get-out-the-vote operation to outside groups, including one funded largely by billionaire Trump ally Elon Musk that’s facing new questions about its practices. Harris’s campaign, by contrast, is running a more traditional operation that features more than 2,500 paid staffers and 357 offices in battleground states alone.

Other races to watch

Despite so much focus on the presidency, voters will also be choosing new members of Congress, who pass laws and initiate spending plans. These two chambers can act as a check on White House plans if the controlling party in either chamber disagrees with the president.

All 435 seats in the House of Representatives and 34 of the 100 seats in the Senate are up for grabs. Together, these will decide the membership of the 119th Congress.

Democrats currently control the Senate 51-49 but face an uphill battle this election. Democratic senators or those who vote with Democrats occupy seven of the eight most competitive seats, including Montana and Ohio, which generally lean Republican.

As of Monday, Republicans are significant favourites to retake Senate control.

The balance of power in the House of Representatives will likely be decided by 43 of the most competitive races, according to the most recent ratings by the Cook Political Report. Republicans could retain control by winning just 12 of the 26 seats rated as toss-ups if they also win seats deemed “likely” or “lean” Republican.

Among the House races to watch closely are the Second and Seventh Districts in Virginia, where polls close at 11 pm UK time. One of these races is to replace Abigail Spanberger, a moderate Democrat who is stepping down to run for governor.

This race may be an indicator of how House Republicans will perform in suburbs that have shifted away from Trump in recent years.

In other races across the country, 13 state and territorial governorships and numerous other state and local elections will take place. Voters in 41 states will also consider a total of 159 ballot initiatives.

Ten states including Arizona, Colorado and Florida have abortion-related measures on the ballot. Florida, North Dakota and South Dakota are considering whether to legalise marijuana.

Could there be unrest?

Harris has said she is committed to free and fair elections and to the peaceful transfer of power. Trump, however, has not pledged to accept the results of the 2024 election, stating he would do so only “if it’s a fair election” and asserting that he can only lose due to fraud.

In recent days, Trump has been aggressively promoting unfounded claims that question the integrity of the election. He falsely maintains that he can only be defeated if Democrats cheat, despite polls indicating a genuinely competitive race.

It is likely Trump could once again declare victory on election night, regardless of the actual results, as he did in 2020. Election officials, who have spent four years dealing with the consequences of his 2020 falsehoods, fear that his current rhetoric could incite violence.

Such inflammatory language can have severe repercussions, as seen when Trump supporters stormed the Capitol on January 6, 2021, one of the darkest days in modern American history.

Election officials are particularly concerned that Trump’s latest claims could incite unrest. There are already reports of election officials being intimidated and threatened this election.

A report from the Global Project Against Hate and Extremism (GPAHE) highlighted alarming trends in online chatter, mirroring patterns observed in the lead-up to the 2020 election and the January 6 Capitol insurrection.

On Tuesday, the Republican National Committee will deploy thousands of “election integrity” poll monitors to look for signs of fraud, which critics warn may result in voter or election worker harassment. In some key polling locations, officials have requested the presence of sheriff’s deputies, as well as the installation of bulletproof glass and panic buttons connected to local 911 dispatchers.

At the same time, Trump’s allies point out that he has survived two assassination attempts in recent months, raising concerns about additional threats against him. Law enforcement in Washington and other cities is bracing for possible unrest on Election Day.

It is important to remember that a broad coalition of top government and industry officials, many of whom are Republicans, concluded that the 2020 election was the “most secure” in American history.

Politics.co.uk is the UK’s leading digital-only political website. Subscribe to our daily newsletter for all the latest news and analysis.