In photos: The US inauguration of Joe Biden

The coronavirus pandemic and threats of violence made the inauguration of the 46th president one of the most unusual in American history.

U.S. President Joe Biden kisses first lady Jill Biden as they stand at the North Portico of the White House, in Washington, D.C., U.S., Jan. 20, 2021.

Some 200,000 American, state and territorial flags were placed on the National Mall to represent people who could not attend because of COVID-19, which has killed 400,000 people in the United States. In the past, the Capitol was packed with thousands trying to witness history.

A general view of the Capitol during the inauguration of Joe Biden as the 46th president of the United States on the West Front of the U.S. Capitol in Washington, D.C., U.S., Jan. 20, 2021.

This year, VIPs were seated several feet (meters) apart, and they wore masks to prevent the spread of the coronavirus. In 1961, the world could see every expression on President John F. Kennedy’s face. In contrast, Biden’s face was covered with a mask except for when he spoke.

First lady Jill Biden places her hands on U.S. President Joe Biden's shoulders during the 59th Presidential Inauguration in Washington, D.C., U.S., Jan. 20, 2021.

The Capitol, the epicenter of democracy that was invaded by violent loyalists of former President Donald Trump just two weeks ago, was surrounded by multiple rings of heavy steel fencing, topped with razor wire. Streets and bridges were closed. Intersections were blocked with dump trucks.

U.S. Vice President Kamala Harris and her husband Doug Emhoff wave after the inauguration of Joe Biden as the 46th president of the United States, in Washington, D.C., U.S., Jan. 20, 2021.

Kamala Harris is sworn in as U.S. vice president as her spouse Doug Emhoff holds a Bible during the inauguration of Joe Biden as the 46th president of the United States on the West Front of the U.S. Capitol in Washington, D.C., U.S., Jan. 20, 2021.

Former U.S. President Barack Obama and former first lady Michelle Obama arrive for the inauguration of Joe Biden as the 46th president of the United States on the West Front of the U.S. Capitol in Washington, D.C., U.S., Jan. 20, 2021.

Joe Biden is sworn in as the 46th president of the United States as his wife Jill Biden holds a Bible on the West Front of the U.S. Capitol in Washington, D.C., U.S., Jan. 20, 2021.

U.S. President Joe Biden signs three documents including an Inauguration declaration, Cabinet nominations and sub-Cabinet nominations, as U.S. Vice President Kamala Harris watches in the President's Room at the U.S. Capitol after the 59th Presidential Inauguration in Washington, D.C., U.S., Jan. 20, 2021.

From left, President Joe Biden, first lady Jill Biden, Vice President Kamala Harris and second gentleman Doug Emhoff arrive at the steps of the U.S. Capitol ahead of the inauguration of President Joe Biden in Washington, D.C., U.S., Jan. 20, 2021.

U.S. President Joe Biden signs executive orders in the Oval Office of the White House in Washington, D.C., U.S., Jan. 20, 2021.

U.S. President Joe Biden, first lady Jill Biden, Vice President Kamala Harris and second gentleman Doug Emhoff depart after the 59th Presidential Inauguration in Washington, D.C., U.S., Jan. 20, 2021.

U.S. President Joe Biden with former U.S President Barack Obama during Biden's inauguration as the 46th president of the United States on the West Front of the U.S. Capitol in Washington, D.C., U.S., Jan. 20, 2021.

Katy Perry (foreground) performs in front of a fireworks display during the "Celebrating America" event at the Lincoln Memorial after the inauguration of Joe Biden as the 46th president of the United States in Washington, D.C., U.S., Jan. 20, 2021.