US election results 2020: When will we know who has won?

It’s been three days since the US election. You might have reasonably expected to have some kind of clue about the results by now.

We still don’t know, because not enough votes have been counted for either Donald Trump or Joe Biden to win.

But it is getting closer.

The huge number of postal votes cast during this pandemic election, and different states’ laws about how to count them, meant this always was going to take longer if the race was tight.

Yes, so far, but that’s not what decides who gets to be president.

Instead, a candidate has to win the majority in a system called the electoral college, where each state gets a certain number of votes or “electors” roughly in proportion to its population. If you win a state, you win all its votes (except Nebraska and Maine, but that’s complicated). There are 538 state votes and the person who gets 270 wins the prize.

But there are several paths to victory for Mr Biden, who is on 253 electoral college votes to Mr Trump’s 214.

If Mr Biden gets Pennsylvania, he is over the line. Georgia and some combination of Nevada, Arizona and Wisconsin works for him too. Mr Trump will need Pennsylvania’s votes and to win three states out of Georgia, North Carolina, Nevada or Arizona.

So how are they doing in these states, and which one looks closest right?

Donald Trump is doing better than expected and Joe Biden has failed to win those battleground states which count votes quickly, but he is closing the gap in a few crucial states as votes get counted.

Each state has its own laws and systems for counting votes. Individual states are also in charge of the order in which they count different types of votes (for example postal votes are often counted last).

That’s why we see such dramatic shifts in who leads a race – Republicans tend to vote in person on the day and postal votes tend to skew Democratic.

Another thing to be aware of is that different news outlets have different tallies for each candidate depending on where they get election data from. So some outlets have called Arizona for Mr Biden, but the BBC thinks its still not decided.

Mr Trump has launched some challenges, but analysts suggest most of these challenges concern small numbers of ballots that might not make a difference in the end, with the exception of Pennsylvania, where the Supreme Court previously hinted it could revisit the rules about deadlines for accepting postal votes.

It now looks like polling data going into this week didn’t tell us the whole story about the American public. Many observers didn’t realise the race would be so tight.

Robert Cuffe, the BBC’s head of statistics, says it’s still too early to say whether this election has been a pollster’s nightmare. Final national polls showed Mr Biden leading Mr Trump by about eight points. In battleground states Mr Biden also polled in the lead, but by a much slimmer margin.

Some experts suspect there’s a part of the American public which won’t even participate in polls because they don’t trust institutions – they’re more likely to vote for Mr Trump.

Voter priorities may have also been slightly misjudged. While the coronavirus pandemic has dominated headlines, a survey conducted by Edison Research found that more voters (one third in total) listed the economy as their key issue – it was a core Trump message.

Mr Trump’s vote also looks a little bit more diverse than many might have assumed.