Where US election will be won and lost

IN just two weeks America goes to the polls in what is likely to be the most defining election in a generation.

- Martyn Brown

If Democrat candidate Kamala Harris wins on November 5 she will become the first female US President in history.

Should Republican rival Donald Trump emerge victorious he will be the first former president to be re-elected after being defeated since Grover Cleveland in 1893. He was the only one to ever have pulled that off.

About 240 million people are eligible to vote in this year's election.

But with the polls so close only a relatively small number of them are likely to decide who becomes the next president.

Experts believe there are only a handful of so-called "swing" states that could plausibly be won by either candidate.

Seven of them - Arizona, Georgia, Michigan, Nevada, North Carolina, Pennsylvania and Wisconsin - hold the keys to the White House.

HOW DOES THE US ELECTORAL SYSTEM WORK?

The US presidential election is decided by the number of electoral college votes, rather than the popular vote.

The candidate to hit the 270 electoral vote mark - a majority of the 538 - wins the US election.

Each state has a number of electoral votes, roughly in line with the size of its population.

California has the most with 54, while a handful of sparsely-populated states such as Wyoming, Alaska and North Dakota, as well as Washington DC, have the minimum of three. Most states award all their electoral college votes to whoever wins the poll of ordinary voters in the state.

For example, if a candidate wins 50.1% of the vote in Texas, they are given all of the state's 40 electoral votes. A candidate who won a state by a landslide would still pick up the same number of electoral votes as if they had won by a tiny margin.

Only Maine and Nebraska can split their electoral college votes.