With bated breath, the world watches as the 2020 US presidential election approaches its end, to see whether incumbent President Donald Trump will once again defy the polls and achieve victory.

After a long night of counting in the US extended well into the next day, with some states still yet to conclude counting, the result is still unclear, though signs point toward a slight lead for challenger Joe Biden, buoyed up by early votes and mail-in ballots.

Though while Biden seems to be comfortably ahead in the popular vote, the US voting system means that a winner can be crowned despite receiving less votes overall.

How does the US voting system work? Electoral college, voting population and swing states explained ahead of presidential election (Photo: Shutterstock)

That’s because elections in the US work differently to in the UK, primarily because they have a presidential election system, where a head of state is elected separately to the lawmakers who sit in Congress, the US equivalent of the UK’s Parliament.

So here’s everything you need to know.

How does voting in the US work?

While there are other parties who stand their own candidates for the presidency, the US basically has a two-party system for presidential elections.

Each main party - Republican and Democrat - selects their candidate through a series of primary elections held in each state, with the exception of a handful of states which run caucuses, which are like local meetings.

But individual voters don’t directly elect their chosen candidates in primary or presidential elections.

In primaries, voters elect delegates, effectively supporters of a certain candidate, with each state assigned a number of delegates based on their population size.

The candidate from each party who picks up the most delegates after these primaries will go on to be the presidential candidate.

What is the electoral college?

In presidential elections, voting members of the public do not vote directly for the president, but vote to elect a group of officials in their state who make up the electoral college.

Each state is assigned a number of electoral votes relative to the number of seats in Congress the state is afforded, which loosely correlates with population size.

In most states, as individual votes are counted, all the electoral votes are assigned to whichever candidate received the most votes.

In practice this means that a candidate can take all the electoral votes from a state, and their opponent can take none, even if the vote was split 51 per cent to 49 per cent.

However, there are two states where electoral votes are distributed proportionally based on the candidates’ vote share - Nebraska and Maine.

The candidate with the highest number of electoral votes when all the states are counted will win the presidency.

US Election 2020: Results so far as Trump vs Biden vote count continues - and hi...

This means that it is possible for a candidate to receive more votes overall than their rival, but still lose the presidency, as was the case in 2016 when Hillary Clinton received more votes than Donald Trump.

There are 538 members of the electoral college, known as electors, with a candidate needing to win half of them plus one to win the election, or 270.

How many electoral votes does each state get?

California - 55

Texas - 38

Florida 29

New York 29

Illinois 20

Pennsylvania 20

Ohio 18

Georgia 16

Michigan 16

North Carolina 15

New Jersey 14

Virginia 13

Washington 12

Arizona 11

Indiana 11

Massachusetts 11

Tennessee 11

Maryland 10

Minnesota 10

Missouri 10

Wisconsin 10

Alabama 9

Colorado 9

South Carolina 9

Kentucky 8

Louisiana 8

Connecticut 7

Oklahoma 7

Oregon 7

Arkansas 6

Iowa 6

Kansas 6

Mississippi 6

Nevada 6

Utah 6

Nebraska 5

New Mexico 5

West Virginia 5

Hawaii 4

Idaho 4

Maine 4

New Hampshire 4

Rhode Island 4

Alaska 3

Delaware 3

District of Columbia 3

Montana 3

North Dakota 3

South Dakota 3

Vermont 3

Wyoming 3

When is the president selected?

While the result of the popular vote and the distribution of electoral votes is typically known shortly after election day, the president is not officially picked until electors meet.

According to US election law: “The electors of President and Vice President of each State shall meet and give their votes on the first Monday after the second Wednesday in December next following their appointment at such place in each State as the legislature of such State shall direct".

This means that this year, the electors will assemble in their state capitals and officially select the next president on 14 December.

Interestingly, presidential elections were originally designed so that the runner-up became the vice-president, but this was changed in 1804.

Which are the battleground or swing states?

Similarly to the UK, the result in many US states is almost a foregone conclusion, such as New York which will almost certainly vote Democrat, and Wyoming, similarly likely to vote Republican.

However there are some states, called battleground or swing states, which are traditionally much more split and harder to predict, with more voters in these places who might potentially vote for either candidate, depending on how the campaigns go.

This means that the path to the presidency almost always relies on a strong showing in these states, meaning presidential candidates often spend a lot of time campaigning in these areas.

The following states are widely considered to be the most contentious states in this election: Arizona, Florida, Georgia, Michigan, Minnesota, Ohio, North Carolina, Pennsylvania and Wisconsin.

What is the voting population of the US?

While the US’ population is around 380 million people, not all of them are eligible to vote.

In the US, non-citizens, some people with felonies and people who are mentally incapacitated are barred from voting

You must be 18 or older on election day, and be registered to vote, in order to cast a vote in the presidential election.

While there is no exact figure for how many people are eligible to vote in the upcoming election, the number of people who are eligible has grown in recent years, peaking at 233.7million in 2018.

However, turnout usually sits at around 55 per cent, and was measured at 138 million in 2016, though is expected to be higher this time around, likely at around 145 million.

How will coronavirus impact voting?

This election has already been impacted severely by the Covid pandemic, from which the US has suffered one of the highest death tolls globally and is still struggling to bring the disease under control.

More voters than ever before are expected to vote early, by mail-in ballot or by going to polling stations and voting in person prior to election day.

Of the Around 70 million votes have been cast early this year, more than half the total turnout in 2016, with 48 million of those cast by mail.

Though there have been some accusations of voter fraud surrounding mail-in ballots in the past, the practice is usually supported by both parties, although Mr Trump has on many occasions suggested that he believes mail-in ballots are fraudulent.

Polling shows that Democrat voters are more likely to vote by mail-in ballot than their Republican counterparts.

The prevalence of mail-in ballots is also likely to impact the time it takes to confirm the election result, which is usually announced on the night of the election, but may take a few days to calculate this year.

What is the Electoral College? How the US voting system works as results are counted in Trump vs Biden presidential election 2020