WASHINGTON - Sworn in as the 46th President of the United States on Wednesday (Jan 20), Mr Joe Biden encouraged a nation riven by unprecedented post-election turmoil and deep social and political divides to embrace unity.
Former senator Kamala Harris was sworn in as Vice-President, making history as the first woman, first African American and first Asian American to assume the nation's second-highest office.
"This is America's day. This is democracy's day. A day of history and hope, of renewal and resolve," said Mr Biden in his inaugural address, two weeks after a mob attacked the Capitol in an effort to overturn his victory. "At this hour, my friends, democracy has prevailed."
He called unity the key to overcoming a raging pandemic that has killed 400,000 people and battered the economy, delivering racial justice, and defeating the rise of white supremacy and domestic terrorism.
"This is our historic moment of crisis and challenge, and unity is the path forward," said Mr Biden.
He called on Americans to "reject a culture in which facts themselves are manipulated and even manufactured", and denounced lies told for power and for profit.
He also had a message of hope for a nation reeling from the ongoing pandemic and fractured by politics.
He said: "Few people in our nation's history have been more challenged or found a time more challenging or difficult than the time we're in now... To overcome these challenges, to restore the soul and secure the future of America requires so much more than words and requires the most elusive of all things in a democracy: unity."
President Biden is set to immediately roll back key policies of former president Donald Trump and will sign a raft of executive orders tackling the pandemic, climate change and immigration.
These include mandating masks on federal property, stopping America's withdrawal from the World Health Organisation, re-entering the Paris climate agreement, halting construction of a border wall and ending the travel ban on some Muslim-majority countries.
Mr Biden promised to repair America's alliances and engage with the world once again, in a rejection of Mr Trump's "America First" isolationist turn.
Mr Biden served as vice-president from 2009 to 2017 under then President Barack Obama, and made two previous presidential runs in his 36 years as Delaware senator.
He staged a late comeback to clinch the Democratic Party nomination and won both the electoral college and popular vote in the Nov 3 presidential election, garnering seven million more votes than Mr Trump.
About 1,000 lawmakers and guests attended the scaled-down and socially distanced ceremony, with a sea of flags on the National Mall replacing the usual crowds of hundreds of thousands who traditionally show up at inaugurations.
Wednesday's ceremony went off without violence in a heavily militarised capital, with 25,000 National Guard troops deployed to Washington DC to lock down the city amid security threats.
The authorities had warned of possible domestic terrorist attacks from armed militia groups and white supremacists, as well as potentially violent pro-Trump protests.
Mr Trump ended his tumultuous four-year presidency with a departure ceremony at Joint Base Andrews before he departed for Florida, the first president in 152 years to skip the tradition of attending his successor's inauguration.
Mr Trump continued to deny that he had lost the elections, continuing to tell his supporters for weeks that it had been stolen from him.
This culminated in a mob assault on the Capitol on Jan 6 that led to his second impeachment for inciting an insurrection.
Prime Minister Lee Hsien Loong and President Halimah Yacob penned letters of congratulations to President Biden, highlighting the long, enduring friendship between Singapore and the US.