Joe Biden will swear the oath of office at noon local time to become the 46th president of the United States, taking the helm of a deeply divided nation and inheriting a confluence of crises arguably greater than any faced by his predecessors.
The very ceremony in which presidential power is transferred, a hallowed US democratic tradition, will serve as a jarring reminder of the challenges Mr Biden faces.
The inauguration unfolds at a US Capitol battered by an insurrectionist siege just two weeks ago, encircled by security forces evocative of those in a war zone, and devoid of crowds because of the threat of the coronavirus pandemic.
Stay home, Americans were exhorted, to prevent further spread of a surging virus that has claimed 400,000 American lives.
Mr Biden will look out over a capital city dotted with empty storefronts that attest to the pandemic’s deep economic toll and where summer protests laid bare the nation’s renewed reckoning on racial justice.
He will not be applauded, or likely even acknowledged, by his predecessor.
Flouting tradition, Donald Trump departed the White House on Wednesday morning ahead of the inauguration rather than accompany his successor to the Capitol.
Mr Trump, awaiting his second impeachment trial, stoked grievance among his supporters with the lie that Mr Biden’s win was illegitimate.
Mr Biden, in his third run for the presidency, staked his candidacy less on any distinctive political ideology than on galvanising a broad coalition of voters around the notion that Mr Trump posed an existential threat to US democracy.
On his first day, Mr Biden will take a series of executive actions — on the pandemic, climate, immigration and more — to undo the heart of Mr Trump’s agenda.
He takes office with the bonds of the republic strained and the nation reeling from challenges that rival those faced by Abraham Lincoln and Franklin D. Roosevelt.
“Biden will face a series of urgent, burning crises like we have not seen before, and they all have to be solved at once. It is very hard to find a parallel in history,” said presidential historian Michael Beschloss.
“I think we have been through a near-death experience as a democracy.
“Americans who will watch the new president be sworn in are now acutely aware of how fragile our democracy is and how much it needs to be protected.”
Mr Biden will come to office with a well of empathy and resolve born by personal tragedy as well as a depth of experience forged from more than four decades in Washington.
At age 78, he will be the oldest president inaugurated.
More history will be made at his side, as Kamala Harris becomes the first woman to become vice president.
The former US senator from California is also the first black person and first person of South Asian descent elected to the vice presidency and will become the highest-ranking woman ever to serve in government.
The two will be sworn in during an inauguration ceremony with few parallels in history.
Tens of thousands of troops are on the streets to provide security precisely two weeks after a violent mob of Mr Trump supporters, incited by the president, stormed the Capitol in an attempt to prevent the certification of Mr Biden’s victory.
The tense atmosphere evoked the 1861 inauguration of Mr Lincoln, who was secretly transported to Washington to avoid assassins on the eve of the Civil War, or Mr Roosevelt’s inaugural in 1945, when he opted for a small, secure ceremony at the White House in the waning months of the Second World War.
Despite security warnings, Mr Biden declined to move the ceremony indoors and instead will address a small, socially distant crowd on the West Front of the Capitol.
Some of the traditional trappings of the quadrennial ceremony will remain.
The day will begin with a reach across the aisle after four years of bitter partisan battles under Mr Trump.
Mr Biden invited Mitch McConnell and Kevin McCarthy, the Republican leaders of the Senate and House, to join him at a morning Mass, along with Chuck Schumer and House Speaker Nancy Pelosi, the Democratic leaders.
Once at the Capitol, Mr Biden will be administered the oath by Chief Justice John Roberts; Ms Harris will be sworn in by Justice Sonia Sotomayor.
The theme of Mr Biden’s approximately 30-minute speech will be America United, and aides said it would be a call to set aside differences during a moment of national trial.
Mr Biden will then oversee a Pass In Review, a military tradition that honours the peaceful transfer of power to a new commander in chief.
Then, Mr Biden, Ms Harris and their spouses will be joined by a bipartisan trio of former presidents — Bill Clinton, George W. Bush and Barack Obama — to lay a wreath at the Tomb Of The Unknown Soldier at Arlington National Ceremony.
Later, Mr Biden will join the end of a slimmed-down inaugural parade as he moves into the White House.
Because of the pandemic, much of this year’s parade will be a virtual affair featuring performances from around the nation.