So what happens if it's a tie?

With the race for the White House going to the wire, there is a real possibility that the vote could end up a tie. Here, the Standard explains what will happen if the American people cannot decide on a president.

What is the Electoral College?

It is the US institution that officially elects the president. The electors are chosen by each of the 50 states and the District of Columbia. The number — 538 — is based on the number of representatives in Congress, and it is made up of 435 members of the House of Representatives and 100 members of the Senate. The extra three electors represent the nation’s capital. Bigger states with more representatives get more electoral votes, thus California gets 55 while tiny Delaware gets three.

What happens if the two men tie at 269 votes each?

The 12th amendment of the Constitution states that if no single candidate gets a majority of the electoral vote, the House of Representatives chooses the winner from the three candidates with the top vote counts. The Senate decides on the vice president. The Republican-led House of Representatives would almost certainly choose Mr Romney as the next president. The Democrat-controlled Senate would most likely plump for Joe Biden. The result? Chaos in Washington.

How long would it take to know who is the next president in the event of deadlock?

Days or possibly weeks because such a close result will result in challenges and recounts in states where the vote was close. After the lawyers became involved in the contest over missing votes in Florida in 2000, it was December 12 before George Bush was declared the winner over Al Gore.

Has there ever been a tie before in a presidential election?

Not since DC was granted three electoral votes to make a 538 total in 1964.

Has the House of Representatives ever chosen the president?

Yes, three times. The first time the House picked the president was in 1800. Thomas Jefferson and Aaron Burr tied with 73 electoral votes each. The representatives flirted with choosing Burr over the man who wrote the Declaration of Independence, but Jefferson finally won after 34 ballots.

Has there ever been a president who lost the popular vote?

Yes, four times, including in 2000 when George Bush squeaked past Al Gore in electoral votes. The others were in 1824, 1876 and 1888.