Top musicians from Bruce Springsteen to Beyonce to Madonna are rallying behind Hillary Clinton in the countdown to Tuesday's election, adding A-list star power to a massive get-out-the-vote operation.

Springsteen, one of the biggest concert attractions in the rock universe, warmed up an election eve rally on Monday in Philadelphia, where he hailed Clinton for her "vision of an America where everyone counts."

"Let's all do our part so we can look back on 2016 and say we stood with Hillary Clinton on the right side of history," Springsteen told the roughly 40,000 people assembled near Independence Hall.

Springsteen, who has long championed the US working class in song but avoided overt politics until 2004, charged that Republican candidate Donald Trump would "prioritize his own interests and ego before American democracy itself."

The rally was the largest ever in Clinton's bid to be America's first woman president.

Springsteen was joined by fellow rocker Jon Bon Jovi as well as President Barack Obama and first lady Michelle.

Bon Jovi was later flying with Clinton to another critical state, North Carolina, for a midnight rally with Lady Gaga.

Madonna meanwhile roused Clinton backers in New York with a surprise outdoor concert, taking out an acoustic guitar to perform hits including "Express Yourself."

"As far as I'm concerned, we still live in an extremely chauvinistic, sexist, misogynist country and that is why Hillary Clinton needs to be president," said Madonna, sporting a knit cap in the design of the US flag.

Madonna voiced dread over the prospect of a Trump presidency, asking the crowd in Washington Square: "Do we want to be the laughing stock of the planet?"