The race for the White House is proving to be very close, so how could each candidate make it over the line?
A candidate needs 270 electoral college votes to win the presidential election.
Each state has a different number of electoral college votes depending on the size of its electorate.
All states except for Nebraska and Maine operate a winner-takes-all system, with the candidate who wins the most votes from the people in a state claiming all of that state's electoral votes.
Here's how the candidates, looking at Joe Biden first and then Donald Trump, could win the all important 270 votes - and what would happen if there is a tie.
Joe Biden's path to 270 electoral college votes
Traditionally a Republican state, Arizona looks like it could flip for just the second time since 1952.
But Mr Biden said he was confident he was on track to take the three key Rust Belt states of Michigan, Wisconsin and Pennsylvania.
Pennsylvania, known as the Keystone State, has 20 electoral votes - the sixth equal highest with Illinois - so will be a big boost for whoever wins it.
If he did win those three states Mr Biden would be up to 259 votes, so would have to win Arizona - a state he is confident of claiming - to clinch exactly 270.
Donald Trump's path to 270 electoral college votes
However, the result from Fulton County, Georgia, may not come out until the afternoon as the count was delayed by a burst water pipe (no ballots were damaged).
How could they tie?
If Mr Biden loses Nebraska but wins Arizona, Michigan and Wisconsin - and Mr Trump wins Pennsylvania - the pair could both have 269 votes.
A tie would also happen if Mr Biden wins everything that Hillary Clinton won in 2016, plus Michigan and Pennsylvania, and one of Nebraska's five electoral votes.
In that case, the newly elected House of Representatives would choose the president and the Senate would choose the vice president.
Each state would get one vote in the House, with a simply majority - 26 votes or more - needed to win.
The last time a tie happened was in 1800, between Thomas Jefferson and Aaron Burr.