Americans go to the polls on Tuesday in an election that is widely dubbed "a referendum on the soul of the nation".
They will decide between Republican President Donald Trump and Democratic rival Joe Biden, who has a steady lead in opinion polls.
Trump, 74, is seeking another four years in office after a tumultuous first term, while Biden, 77, is looking to win the presidency after a political career spanning five decades, Reuters reports.
Biden also served for eight years as vice president under Trump’s Democratic predecessor, Barack Obama. He mounted unsuccessful bids for the Democratic presidential nomination in 1988 and 2008, the agency adds.
This US election, marked by fear and rancour, has turned out to be one of the most bitter and divisive ones in decades.
"The election has become a referendum on the soul of the nation," New York Times writes in a recent article titled "Biden and Trump Say They’re Fighting for America’s ‘Soul.’ What Does That Mean?."
"It is a phrase that has been constantly invoked by Democratic and Republican leaders. It has become the clearest symbol of the mood of the country, and what people feel is at stake in November. Everyone, it seems, is fighting for it," the newspaper says.
The first polls are scheduled to begin at 05:00 EDT (10:00 GMT) in Vermont, a northeastern state in the New England region of the United States.
Voters in the US election have no role in deciding an overall single national candidate. They only decide state-level election frays.
In its electoral college system, each state gets a certain number of votes on the basis of its population.
As a total of 538 votes are up for grabs, a candidate must win at least 270 votes in the electoral college to be elected president.
That means even after winning the most votes in the election nationally, a candidate may lose an election, as Hillary Clinton did in 2016.
The voting caps a campaign dominated by the coronavirus pandemic that has killed more than 231,000 Americans and put millions out of work, according to Reuters news agency.
During the election campaign, the US also witnessed nationwide protests over racial injustice against Black Americans, it says.
Biden has promised a renewed effort to combat the health crisis, fix the economy and bridge America’s political divide.
But, it says, Trump is close in enough swing states to possibly piece together the 270 state-by-state Electoral College votes needed to win the presidency.
More than 98 million early votes have already been cast in person or by mail, Reuters says citing the US Elections Project at the University of Florida.
It is a record-setting pace fuelled by intense interest in the high-stakes election and concerns about voting in person on Election Day during a pandemic, according to the news agency.
The number is equal to about 71.4 per cent of the entire turnout in 2016 and represents about 40 per cent of all Americans who are legally eligible to vote, it notes.
Trump has questioned the integrity of the election results for months, making unsubstantiated claims that mail-in voting is rife with fraud and refusing to commit to a peaceful transfer of power if he loses, according to Reuters.
Trump was quoted as saying votes should only be counted through election night, even though many states often take days or weeks to tally ballots.
The uncertainty and the prospect of prolonged legal battles have fuelled unprecedented anxiety about the election’s outcome and aftermath, Reuters reports.
Quoted by police, it says several cities are boarding up buildings in anticipation of possible protests, including around the White House and in New York City.
The famed shopping destination of Rodeo Drive in Beverly Hills, California, will be closed on Tuesday, the news agency adds.
Americans will also decide on Tuesday which political party will control the US Congress for the next two years, with Democrats pushing to recapture a Senate majority and expected to retain their control of the House of Representatives, according to Reuters.
