Joe Biden took charge as the 46th president of the United States on Wednesday with an upbeat call to heal a nation torn by deep schisms as he immediately erased some of Donald Trump's most divisive policies.

President Donald Trump will leave on Marine One, then go to Florida
President Donald Trump will leave on Marine One, then go to Florida AFP / SAUL LOEB

Standing on the steps of a US Capitol that was ransacked exactly two weeks earlier by pro-Trump mobs seeking to overturn his victory, Biden swore the presidential oath on a bulging century-old family Bible moments after Kamala Harris officially became America's first woman vice president.

"Democracy is precious, democracy is fragile and at this hour, my friends, democracy has prevailed," Biden said before a National Mall that was virtually empty due to the ultra-tight security and a raging Covid-19 pandemic that he vowed to confront swiftly.

President Donald Trump has one last full day in the White House
President Donald Trump has one last full day in the White House AFP / MANDEL NGAN

"We must end this uncivil war that pits red against blue, rural versus urban, conservative versus liberal. We can do this if we open our souls instead of hardening our hearts, if we show a little tolerance and humility and we're willing to stand in the other person's shoes," he said.

"Together we shall write an American story of hope, not fear, of unity, not division, of light, not darkness. A story of decency and dignity, love and healing and goodness."

Final preparations are underway at the US Capitol for  a socially distanced inauguration
Final preparations are underway at the US Capitol for a socially distanced inauguration POOL / Caroline Brehman

But Trump, who falsely said that he was cheated out of a second term and egged on his supporters before their deadly rampage at the Capitol, broke 152 years of tradition by refusing to attend his successor's inauguration.

Biden pushed through a flurry of orders the moment he entered the White House, starting with rejoining the 2015 Paris climate accord, from which the US withdrew under Trump, an ally of the fossil fuel industry.

Donald Trump is largely out of sight in his final days as president
Donald Trump is largely out of sight in his final days as president AFP / Brendan Smialowski

"We are going to combat climate change in a way we have not done so far," the new US leader said in the Oval Office as he signed papers on the Paris deal, which was negotiated by Barack Obama when Biden was his vice president.

Biden's spokeswoman Jen Psaki said his first call to a foreign leader would be on Friday to Canadian Prime Minister Justin Trudeau -- after Biden blocked the Keystone XL pipeline fiercely opposed by environmentalists but backed by Ottawa.

The movers are busy at the White House
The movers are busy at the White House AFP / MANDEL NGAN

Biden also halted the US exit from the World Health Organization, stopped construction of Trump's cherished wall on the Mexican border and rescinded a ban on visitors from several Muslim-majority nations.

"As a nation built on religious freedom and tolerance, we welcome people of all faiths and those of no faith at all. It is who we are," said the new State Department spokesman, Ned Price.

Joe Biden is two days before becoming president
Joe Biden is two days before becoming president AFP / JIM WATSON
US President-elect Joe Biden is on his way to Washington
US President-elect Joe Biden is on his way to Washington AFP / Angela Weiss

In his inaugural address, Biden appealed to supporters of Trump, who shattered political norms by ruthlessly belittling rivals, denouncing entire ethnic groups and trying to cast doubt on basic facts.

"I will be a president for all Americans," the veteran Democrat said.

Joe Biden and Kamala Harris arrive at the Capitol for inauguration ceremony
Joe Biden and Kamala Harris arrive at the Capitol for inauguration ceremony DC POOL / Sébastien VUAGNAT

But Biden confronted head-on the rise of domestic extremism, as evidenced during Trump's presidency by the Capitol assault, deadly attacks on synagogues and immigrants, and a violent march by neo-Nazis in Charlottesville, Virginia.

The United States faces "a rise of political extremism, white supremacy, domestic terrorism that we must confront, and we will defeat," Biden said.

Preparations for the inauguration of US President-elect Joe Biden on January 20, 2021
Preparations for the inauguration of US President-elect Joe Biden on January 20, 2021 AFP / ROBERTO SCHMIDT

"Our history has been a constant struggle between the American ideal that we are all created equal and the harsh ugly reality that racism, nativism, fear and demonization have long torn us apart."

At 78, Biden is the oldest-ever US president, a job he first sought in 1987, and is only the second Roman Catholic president after John F Kennedy.

Biden calls for 'unity' in inauguration speech
Biden calls for 'unity' in inauguration speech DC POOL

Harris, the daughter of Indian and Jamaican immigrants, became the highest-ranking woman in US history, and the first Black person and first person of Asian heritage as the nation's number two.

She and her husband Doug Emhoff -- America's first-ever "second gentleman" -- were escorted to the inauguration by Eugene Goodman, a Black police officer at the Capitol who became a hero by luring away the mostly white mob away from the Senate chambers.

US President Joe Biden's cabinet nominees and senior advisors
US President Joe Biden's cabinet nominees and senior advisors AFP / Jonathan WALTER

Thanks to the new vice president's tie-breaking vote, the Democratic Party regained control of the Senate, which confirmed the first of Biden's nominees, national intelligence chief Avril Haines.

Washington took on the dystopian look of an armed camp, protected by some 25,000 National Guard troops who sealed off the city center.

With the public essentially barred from attending the proceedings, Biden's audience instead was 200,000 flags planted to represent the crowds absent from the National Mall.

Biden, who has vowed a major escalation in the nation's Covid vaccination drive, warned that the "toughest and deadliest period" was still ahead.

So far, more than 400,000 people have died of Covid in the United States, more than in any other country.

"We must set aside politics and finally face this pandemic as one nation," he said, striking a new tone after Trump's mockery of mask-wearing and business closings meant to halt the virus.

While the public crowds were gone, Biden brought in celebrity power -- absent four years ago with Trump.

Lady Gaga, in a dress with a black bodice and a billowing red skirt, sang the national anthem and Jennifer Lopez gave a pop rendition of "This Land is Your Land," ending by exclaiming the final words of the pledge of allegiance -- "one nation, under God, indivisible, with liberty and justice for all" -- in Spanish.

The new first lady, Jill Biden, invited a 22-year-old poet, Amanda Gorman, who became a star of the day with verse on how democracy "can never be permanently defeated."

In lieu of inaugural balls, Biden joined a prime-time television broadcast from the Lincoln Memorial that featured Bruce Springsteen, Bon Jovi, a number of Broadway stars and Justin Timberlake -- some live at the monument, but many of them appearing from remote locations.

Biden and Harris started their administration by jointly paying respects to fallen soldiers at Arlington National Cemetery followed by an inaugural parade -- without spectators -- that featured both an Army fife and drum corps in the red coats of George Washington's time, and a drumline and dancers from Howard University, the historically Black institution that counts the new vice president as a graduate.

Trump left Washington hours before the inauguration, walking on a red carpet on the White House lawn with his wife Melania into the Marine One presidential helicopter, which flew near the inauguration-ready Capitol before heading to Andrews Air Force Base.

"This has been an incredible four years," Trump told several hundred cheering supporters at a campaign-style event with cannons before leaving for his Florida resort in his last trip on Air Force One.

"We will be back in some form," vowed Trump, who retains a hold on much of the Republican Party despite being the first president to be impeached twice.

In a first hint of graciousness, Trump wished the next administration "great luck and great success" -- without saying Biden's name.

Biden said that Trump left him a traditional letter that was "very generous" but declined to reveal the contents.