The country is more divided and angry than at any time since the Vietnam War era of the 1970s and fears that Trump could dispute the result of the election are only fueling those tensions.

Despite an often startlingly laid-back campaign, Biden leads in almost every opinion poll, buoyed by his consistent message that America needs to restore its "soul" and get new leadership in the midst of a coronavirus pandemic that has killed more than 231,000 people.

"I have a feeling we're coming together for a big win tomorrow," Biden said in Pittsburgh, Pennsylvania, a vital electoral battleground where he was joined by pop superstar Lady Gaga. "It's time to stand up and take back our democracy."

But Trump was characteristically defiant to the end, campaigning at a frenetic pace with crowded rallies in four states on Monday, and repeating his dark, unprecedented claims for a US president that the polls risk being rigged against him.

While Tuesday is formally Election Day, in reality, Americans have been voting for weeks.

eNCA