Millions of Americans head to the polls today to cast their vote for who they want to become the next president of the United States.
However, the candidate who receives the most votes from the American people may not be the person who ends up in the White House.
That’s because the US president is not directly elected by popular vote – they are elected by something called the electoral college.
More: What to know about US election day
Here’s everything you need to know about how the president is elected.
What is the electoral college?
In the presidential election, each of America’s 50 states (and Washington DC) are allocated a number of electoral college votes – 538 in total.
The number of votes which each state has roughly depends on its population size – California is the state with the highest population and so it has most electoral votes at 54, while states with sparse populations, such as Alaska and North Dakota, have the minimum of three votes each.
Generally, whoever wins the most votes in each state will win that state’s electoral votes.
For example, if Kamala Harris wins California as she is expected to, she will receive all 54 votes.
The system is called the ‘electoral college’ because each state has a group of people who are responsible for casting their states votes – they are known as ‘electors’ or collectively as a ‘slate’.
The electoral college has been part of the US Constitution since it was drawn up; at the time it was included as a popular vote across the nation was practically impossible due to the size and lack of communication methods.
Why do candidates need 270 votes to win?
In order to become president, either Kamala Harris or Donald Trump will need to reach the ‘magic number’ of 270 electoral college votes.
Once a candidate reaches 270 votes, it is no longer mathematically possible for their opponent to win the White House.
Technically, it is be possible for there to be a tie in electoral votes - this last happened back in 1824, when the votes were split between four candidates and none of them had a clear majority.
In this instance, the House of Representatives votes to elect the president; however, this is very unlikely to happen in the modern era with the bipartisan dominance of the Democrats and Republicans.
Do state electors have to vote for the candidate who won the most votes in their state?
It is possible for electors to vote for their preferred candidate, even if it’s not the candidate who won the popular vote in their state.
It is rare for this to happen and in some states, electors are bound by law to vote in accordance with the popular vote.
However, in 2016, several electoral college votes went to the candidate who didn’t win their state and, while not affecting the outcome of the election, some electors were subsequently disqualified and fined or replaced.
States have differing processes for how they choose their electors.
Is it possible to win the most votes overall and not the electoral college?
Yes – this happened in five previous elections and most recently in 2016.
On that occasion, Hillary Clinton received 65.8m votes across the US compared to Trump’s 62.9m.
However, Trump managed to win a lot of tight races in specific states and ended up winning 304 electoral college votes to Clinton’s 227.
For example, in Florida, Trump won the state’s 29 electoral college votes after receiving only 100,000 more votes at the polls.
Winning individual states is ultimately how a candidate wins the presidency.
