US voters are deciding between Trump and his Democratic challenger Joe Biden, along with all 435 seats of the House of Representatives and 35 of the 100 seats in the Senate.
Some 239 million people are eligible to vote this year. The mail-in ballots could take days to be counted – meaning a winner might not be declared in the hours after polls close on Tuesday.
A presidential candidate needs to secure a minimum of 270 out of 538 electoral votes to win the White House.
Voting across the US was largely smooth as voters lined up early in the morning across polling stations in the country to cast their ballots in one of the most consequential and polarised elections in US history that took place in the shadow of a devastating coronavirus pandemic.
The pandemic as well as a strong drive among Americans to have their voices heard on the ballot box resulted in a record 101 million early votes cast in person and by mail before the polls even opened on Election Day.
The New York Times reported that the 2020 presidential campaign was shaping up to be one for the record books, on pace to attract the highest turnout in more than a century.
The NYT quoted University of Florida professor Michael McDonald, who compiles data from across the nation, as saying that America appeared to be on track to see roughly 160 million total votes cast. “That would mean a turnout rate of about 67 per cent of the eligible voting population — higher than the United States has seen in more than a century,” the NYT said, adding that the last time the turnout was more than 65 per cent was 1908, according to the United States Elections Project.