Joe Biden is to be sworn in as US president, taking the helm of a nation wracked by political division, economic anguish and an unrelenting pandemic.
Vice-President-elect Kamala Harris will take the oath of office alongside him in Washington DC, which has been fortified amid fears of civil unrest.
Some 25,000 troops will guard the inauguration ceremony after a deadly riot at the Capitol earlier this month.
Donald Trump will leave the White House for the last time, bound for Florida.
He will not be attending the inauguration ceremony.
Mr. Biden will be sworn in as 46th president of the United States by Supreme Court Chief Justice John Roberts shortly before midday (17:00 GMT) on Wednesday outside the US Capitol.
Due to Covid-19 restrictions, the ceremony will be bereft of the cheering throngs of well-wishers traditional at inaugurations. It will also see extra-tight security after the US Capitol was breached by violent pro-Trump protesters on January, 6.
Among those present will be three former presidents, Barack Obama – whom Mr Biden served for eight years as vice-president, Bill Clinton and George W Bush.
Outgoing Vice-President Mike Pence will also attend the ceremony, skipping Mr Trump’s farewell event at a military base outside the nation’s capital.
Aides say Mr. Biden, a Democrat, will use his inaugural address of about half an hour to deliver an optimistic call for national unity after his Republican predecessor’s turbulent tenure.
Vice-President-elect Harris will be sworn in, becoming the first woman and the first black and Asian-American elevated to serve in a role a heartbeat from the presidency.
There will be musical performances from Lady Gaga – who will sing the national anthem – Jennifer Lopez and Garth Brooks.
An evening concert at the Lincoln Memorial in the city will be hosted by Tom Hanks and include Bruce Springsteen, John Legend, Jon Bon Jovi, Justin Timberlake, and Demi Lovato.
Mr Biden, a Catholic, plans to attend Mass on Wednesday morning at a cathedral in the city with the four top congressional leaders – Republicans and Democrats.
Trump will become the first president not to attend his successor’s inauguration since Andrew Johnson snubbed Ulysses S Grant in 1869.
[Former US President Donald Trump].
He will host a farewell ceremony at Joint Base Andrews in Maryland on Wednesday morning before catching a final flight on Air Force One to begin post-presidential life at his Mar-a-Lago golf club in Palm Beach.
[More reports from BBC].