Inauguration Day comes just two weeks after the deadly insurrection at the U.S. Capitol by pro-Trump extremists. Trump for months refused to accept the results of the 2020 election, citing debunked conspiracy theories of widespread voter fraud.
Biden's oath of office and inaugural address occurred in a locked-down Washington with heavy security, including 25,000 National Guard troops on hand to ensure the peaceful transfer of power.
The ceremony was socially distanced with far fewer attendees than is typical as the coronavirus pandemic rages on. Covid-19 has killed more than 400,000 Americans since the pandemic began early last year.
Biden is now the oldest president in history at 78. Vice President Kamala Harris is America's first female, Black and South Asian American vice president.
Trump broke from precedent by refusing to attend Biden's inauguration ceremony. The former president left the White House and delivered a farewell address Wednesday morning to a small crowd at Joint Base Andrews before boarding Air Force One for the last time and traveling to Florida.