The United States is on track to record its highest voter turnout in more than a century, with at least six states already surpassing their vote totals from 2016.
As polls closed across the country and counting began, President Donald Trump and Democratic challenger Joe Biden were locked in tight races in battleground states.
Millions of voters braved their concerns about COVID-19 and long lines to turn out in person on election day.
They joined more than 101 million Americans who chose to vote early in person or by postal ballot this year, according to the . Nationally, that was already 73.4 per cent of the total votes counted in the 2016 election.
While final turnout numbers won't be known for some time, project lead Michael McDonald, a University of Florida professor, said the total number of 2020 votes had already surpassed 2016 numbers in six states: Colorado, Hawaii, Montana, Oregon, Texas and Washington state.
Mr McDonald estimates the country is on track to cast roughly 160 million votes, which would equal a turnout rate of about 67 per cent of the country's electorate - the highest since at least 1916.
The , with only 55 per cent of eligible voters turning out in the last presidential election.
Most modern presidential elections have a turnout rate of between 50 and 60 per cent, yet this has fluctuated over the years based on who has the right to vote, whether those people are actually able to vote and how high voters perceive the election stakes to be.
David Smith, a senior lecturer at the University of Sydney's US Studies Centre, the question this year would be "how big" the increase in voter turnout is.
An election worker helps to secure ballots at Ford Field on 3 November in Detroit, Michigan. Source: Getty
But John Fortier, director of government studies at the Bipartisan Policy Centre think tank in Washington, the huge early voting numbers may not translate into a record-breaking turnout overall.
The coronavirus pandemic, which continues to ravage the US, has likely been a significant driver in the spike in postal votes as many Americans seek to avoid further outbreaks.
Democrats typically outperform Republicans in mail voting, while the GOP looks to make up ground in election day turnout.
With additional reporting by AFP.