Whoever becomes the next US president will make history.
Democrat Hillary Clinton, 68, would be the first female in the top role while, at 70, Republican Donald Trump would be the oldest person to assume the presidency.
Here are some of their key moments in the race for the White House:
:: July 19
Businessman Donald Trump is declared the official Republican candidate, having pledged a year earlier to "make America great again" when he announced his intention to run.
:: July 26
Hillary Clinton is declared candidate for President at the Democratic National Convention in Philadelphia, fending off stiff competition from her rival Bernie Sanders who gave his public backing saying he was "proud to stand with her".
:: August 12
Clinton and her husband former President Bill Clinton release their tax returns, showing they earned 10.6 million dollars (£8.2 million) last year. Trump continues to refuse to make public details of his own finances, breaking tradition with previous campaigns, saying he will not reveal them before a routine audit is completed.
:: September 11
Clinton has to leave a memorial event for 9/11 victims early. Video footage appears to show her being helped by aides after she stumbles outside and it later emerges she had been diagnosed with pneumonia.
In a sharp rebuke to Trump during the first of three presidential debates she ensures him she has the "stamina" to be the country's next leader.
::: October 7
Trump's bid is plunged into crisis when a 2005 tape emerges in which he is heard talking about groping women and saying he could "grab them by the pussy" because he was a celebrity.
He apologises after the tape sparks outrage but deems it "nothing more than a distraction" from the campaign.
A number of women come forward in the weeks following the tape leak, accusing Trump of unwanted advances or sexual assault. He denies all allegations, saying he believes the election is being rigged against him.
:: October 20
In the third and final debate Trump suggests he may not accept the election result. When pressed on it later he assures those gathered at a rally in Ohio that he will accept the final vote "if I win".
He says he will not commit to honouring the result because he wants to reserve his right to file a legal challenge "in the case of a questionable result".
During the debates the candidates exchanged jibes on various issues, including Clinton referring to Trump as a "puppet" of Russian president Vladimir Putin, and the Republican labelling his Democrat rival a "nasty woman".
:: October 28
The FBI announces it will look at whether there is classified information contained in newly discovered emails, to see if they are relevant to its investigation into Clinton's private email server. It closed its probe into her handling of classified information without filing charges in July.
Clinton maintained there has been no wrongdoing and urged an urgent release of all the relevant information, while Trump praised the FBI, saying the election "might not be as rigged as I thought".
The gap in public opinion polls narrows, but Clinton remains in the lead.