Joe Biden and Kamala Harris sworn in

Joseph R. Biden, Jr., has been sworn in as the 46th president of the United States, taking the reins of power at a perilous time in American history as a bitterly divided country grapples with the deadliest pandemic in a century.

Joe Biden and Kamala Harris sworn in

With his hand on a Bible that has been in his family for generations, Mr. Biden vowed to “preserve, protect and defend the Constitution of the United States” as Chief Justice John Roberts issued the oath of office.

Vice President Kamala Harris, a daughter of immigrants, was sworn in by Sonia Sotomayor, the nation’s first Latina Supreme Court justice,

Joe Biden and Kamala Harris sworn in

making history as the first woman and person of color to become second in line to the presidency.

The inauguration ceremony was unlike any the country has ever seen, with a new president addressing an empty National Mall while thousands of National Guard troops stood watch over downtown Washington. The Mall was filled with thousands of small flags representing Americans who might otherwise have been in attendance, were it not for the pandemic.

Joe Biden and Kamala Harris sworn in

Mr. Biden takes over at a time of tremendous upheaval and division, fueled both by his predecessor and the coronavirus pandemic that has claimed the lives of more than 400,000 Americans.

Members of Congress, Supreme Court justices and outgoing Vice President Mike Pence were on hand to witness Mr. Biden’s swearing-in, with seats spaced apart to prevent the spread of the virus. Three former presidents — Barack Obama, George W. Bush and Bill Clinton — were also among those in attendance.