When we will know who won the US presidential election

The 2024 US presidential election is here, with millions of Americans already casting their ballots.

Polls have shown the race on a knife's edge between Donald Trump and Kamala Harris, with little to indicate which of the two will emerge as the winner.

9news.com.au will be live-blogging the results as they come in on election day. For now, here are some things to know.

When is the US election?

Election Day is Tuesday, November 5. The US government sets the election date as "the Tuesday next after the first Monday in November".

Elections in the US are held on Tuesday on the expectation that voters could attend church on Sunday, travel to the polling location on Monday, vote on Tuesday, and be able to be at the market on Wednesday to sell the food they had grown on their farms.

Because of the time difference, much of election day itself will take place on Wednesday morning Australian time.

READ MORE: What would a Kamala Harris presidency mean for Australia?

When does voting end?

Polling places start to close at 10am Wednesday AEDT.

Results will start to come in soon after that.

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The times polls close is decided state by state, with most of Indiana and Kentucky closing before anywhere else.

But Indiana and Kentucky will almost certainly vote for Donald Trump, and there won't be much to deduce from those states' results.

LIVE UPDATES: Rolling coverage of the 2024 US election

In the following two hours, polls will close and votes will start getting counted in Pennsylvania, Michigan, Georgia and North Carolina.

A candidate which wins at least three of those states will almost certainly become the next president.

By 4pm, the final polls will have closed in Alaska and Hawaii.

READ MORE: US election poll-tracker: Who will win on November 5?

When will we know the results of the US election?

The first results will start coming in relatively soon after polls close in any given state.

In some states, exit polling from media outlets will lead to some states being called immediately.

We can expect states like West Virginia and Tennessee being called for Donald Trump as soon as they close. Same goes with Massachusetts and Vermont for Kamala Harris.

But for states where things are close, it will take a lot longer.

Election day ballots, early ballots and mail-in ballots are usually counted separately.

And because Democrats are historically more likely to vote early, we should expect results to swing from one side to the other depending on which ballots are counted first.

READ MORE: The seven states that actually matter on election day

When has the winner of previous elections been called?

Because there's no centralised body counting ballots nationwide, there's no official declaration of who wins the presidency for several weeks after the election.

However, media outlets like Associated Press will tally votes as they are reported and make calls state-by-state based on their forecasts.

Because these outlets stake their reputations on being correct, they will wait until they are unshakably confident in an outcome before they make their call.

When the election will be called entirely depends on how long it takes to count ballots.

In 2008, Barack Obama's victory was apparent within hours.

While things were close in 2016, Trump was declared the winner on election night itself.

In 2020, it took four days before Joe Biden was named the winner. 

While Biden won in 2020 by more than Trump did in 2016, the sheer volume of mail-in ballots used during the pandemic made for a much slower count.

So we could know the result within hours, or in a matter of days. With polls as close as they are, anything could happen.

9news.com.au will be live-blogging election results as they come in from the United States starting on Wednesday morning.