Key moments from the inauguration of Joe Biden as 46th US president

Biden spoke about uniting a divided country.

The ceremony that made Joe Biden as the 46th president of the United States was an inauguration like never before.

Wednesday marked the first time in more than 150 years that a sitting president didn't attend the swearing-in of his successor. Also absent were the morning traditions involving the outgoing and incoming presidents and their spouses meeting on the North Portico of the White House and sharing a limousine to the ceremony.

And for the first time in history, inauguration attendees, including lawmakers and former Presidents Bill Clinton, George W. Bush and Barack Obama, were forced to wear masks due to the ongoing COVID-19 pandemic, which has now taken the lives of more than 400,000 Americans. Two weeks after an angry mob of pro-Trump rioters stormed Capitol Hill, some attendees even wore body armor.

Here are more key moments from Inauguration Day:

Trump leaves the White House for the last time

Donald Trump didn't invite Biden to the White House prior to the inauguration ceremony.

The embattled president left the White House for the last time Wednesday morning alongside outgoing first lady Melania Trump.

Trump's family applauded as he boarded Air Force One for the last time. He flew to Palm Beach International Airport, where his supporters lined the streets in a show of support as he made his way toward Mar-a-Lago.

The 45th president did leave a note for the 46th, despite speculation that he may forgo that tradition as well.

Biden, Kamala Harris sworn in

Harris, the first woman and person of color to ever hold the office of vice president, was sworn in by Justice Sonia Sotomayor, the first Latina member of the Supreme Court.

Chief Justice John Roberts later administered the presidential oath to Biden as Jill Biden held the bible and as his children, Hunter Biden and Ashley Biden, stood by.

Sen. Amy Klobuchar then introduced Biden for the first time as president.

In his inaugural address, Biden spoke about the "cause of democracy."

"We've learned again that democracy is precious. Democracy is fragile," he said. "And at this hour, my friend, democracy has prevailed."

Biden discussed his hope for uniting a divided country.

"Every disagreement doesn't have to be the cause for a total war," he said, later stating that he would be a president of "all Americans" and would fight "just as hard" for people who did not support him.

Celebrity guests showed their support

Lady Gaga, equipped with a giant dove brooch and microphone, both in gold, performed a rendition of the national anthem.

Jennifer Lopez crooned a mash-up of "This Land is Your Land," "America the Beautiful" and her own single, "Let's Get Loud."

And country star Garth Brooks performed "Amazing Grace."

Youngest person to read poem at inauguration steals the show

Amanda Gorman, a 22-year-old poet from Los Angeles, became the youngest person to read a poem at an inauguration after Biden was sworn in.

Gorman read the piece, "The Hill We Climb," which she wrote after the siege on Capitol Hill on Jan. 6.

"We've seen a force that would shatter our nation rather than share it, would destroy our country if it meant delaying democracy," she read. "And this effort very nearly succeeded. But while democracy can be periodically delayed, It can never be permanently defeated. In this truth, in this faith, we trust. For while we have our eyes on the future, history has its eyes on us."

Gorman was named the first Youth Poet Laureate of Los Angeles in 2014 and the country's first National Youth Poet Laureate three years later.

Biden accompanied by former presidents at Arlington National Cemetery

Biden was greeted with a 21-gun salute when he arrived at Arlington National Cemetery in Virginia.

Former Presidents Bill Clinton, George W. Bush and Barack Obama, along with former first ladies Hillary Clinton, Laura Bush and Michelle Obama, were present when Biden and Harris laid a wreath at the Tomb of the Unknown Soldier.

Trump was notably missing from the row of former presidents. Former President Jimmy Carter, who is 96 years old, sent his well wishes but was unable to travel due to COVID-19 concerns.

Presidential escort to White House

President Joe Biden received his first presidential escort to the White House, but without throngs of supporters on the sidelines to cheer him on.

The route from 15th Street to the White House was heavily guarded by every branch of the U.S. military, joining about 25,000 National Guard troops spread throughout the capital.

Toward the end of the route, Biden was joined by his family after exiting "The Beast," the presidential state car now adorned with the license plate "46," and walked the rest of the way to 1600 Pennsylvania Ave. before entering the White House for the first time as president.

Democrats take control of the Senate

Among Harris' first official acts as vice president was swearing in new members of the U.S. Senate.

The incoming senators included her successor from California and the two Democratic winners of Georgia's runoff races. With the Senate now a 50-50 split, Harris can cast tiebreaking votes.

Sen. Chuck Schumer, D-N.Y., is the new majority leader, and Sen. Mitch McConnell, R-Ky., is the new minority leader.

More star power at 'Celebrating America'

Wednesday evening's "Celebrating America" inaugural program featured more celebrity support for the new administration, from host Tom Hanks to Bruce Springsteen, who kicked things off from the Lincoln Memorial with a performance of "Land of Hope and Dreams."

Other musical acts included Jon Bon Jovi (with a cover of "Here Comes the Sun"), Ant Clemons and Justin Timberlake ("Better Days"), the Foo Fighters ("Times Like These"), John Legend (performing a cover of Nina Simone's "Feeling Good"), Tim McGraw and Tyler Hubbard (with their new song "Undivided") and Demi Lovato (with a cover of Bill Withers' "Lovely Day").

Celebrity chef Jose Andres addressed the food insecurity crisis during the pandemic, and "Hamilton" composer Lin-Manuel Miranda recited a poem by Seamus Heaney that has inspired Biden.

Katy Perry closed out the event singing "Firework" at the Lincoln Memorial as, fittingly, fireworks went off behind the Washington Monument.