An armored black limousine idled on the street as it waited to take Joe Biden to church, where he would begin the first day of his presidency with a prayer for America. Across Pennsylvania Avenue, Biden’s twice-impeached predecessor strode onto the White House’s South Lawn and, on the last day of his presidency, began a journey to a private club in Florida, far away from the capital he was leaving in crisis.

The green rotors whirred atop Marine One, lifting Donald Trump high above the locked-down city beneath him, its streets fortified behind black steel fencing and its most sacred sites surrounded with razor wire. For days, much of downtown Washington had been quiet but for the rumble of military generators and the patter of National Guard members’ boots against pavement. The helicopter’s roaring engines cracked the silence.

On the National Mall, where in an ordinary year hundreds of thousands of people would have packed in to witness history, the public was barred from entering. Instead, troops clad in camouflage and gripping M4 rifles peered up from Constitution Avenue into the gray-sky morning until Marine One disappeared from view.

When the thwack-thwack-thwack reached the airspace above Capitol Hill, the residents there knew what it meant. Trump was leaving. In a city where he had earned just 5 percent of the vote, people cheered and smiled and waved their hands in the air. A jogger on East Capitol yelled, and a man walking his lanky hound whooped. The sound of joy, and relief, rippled across Lincoln Park, passing by RFK Stadium and trailing the outgoing president toward the Anacostia River.

“I had to be here,” said Yvette Best, 53, who had flown in from Orlando the night before. “This is history.”

The city and nation’s attention would soon turn to Trump’s successor, whose inauguration began just as streaks of sunlight finally broke through the clouds. Reminders of the nation’s trauma were all around him, but so, too, were the symbols of hope Biden longed to deliver.

On the Mall before him stood 191,500 U.S. flags representing the people who could not attend amid a still-raging pandemic that, as of this week, has taken 400,000 lives.

Capitol Police Officer Eugene Goodman, the Black man who held off White rioters from entering the Senate chamber Jan. 6, escorted Vice President-elect Kamala D. Harris to her seat. She would later be sworn in by Justice Sonia Sotomayor, the Supreme Court’s first Latina.

In a security line a mile away, Daisha Manning, 27, watched from her phone. She had traveled with two friends from Fort Worth but couldn’t get close enough to see the stage. Ten others crowded around her on the street.

“Oh my God, I’m going to cry,” Manning said, tilting her head up. Her friend, quiet, dabbed at cheeks smudged black with eyeliner. Her brown cloth mask was wet with tears. The women, who were all Black, held on to each other.

All over the city, African Americans rejoiced, especially at Black Lives Matter Plaza, where demonstrators were still allowed, despite the heavy security.

Nadine Seiler twirled around to face the White House with her middle finger in the air before putting it down, laughing and pumping her first.

“Wait, whoops!” she said. “Can’t give the White House a finger anymore.”

Seiler, 55, had been at the same spot over the summer when Trump ordered the area cleared so he could pose for a picture with a Bible across the street. Her eyes stung from the tear gas for hours.

“We are done with him,” she said. “Done with him in our psyche.”

Now, Seiler said, she could finally exhale because a new man — a good man — would be in charge.

“This is America’s day. This is democracy’s day,” Biden said, speaking in front of the 228-year-old building where it had been attacked exactly two weeks earlier.

In Trump’s first speech as president, he had vowed to end “American carnage,” but it was his words inciting actual carnage that led to an inauguration resembling none other in modern history. After the deadly attempted insurrection, 25,000 American troops — uniformed, masked and armed — were called to Washington not to protect the new president from foreign enemies but from other Americans.

Not since Abraham Lincoln’s inauguration in 1861, one month before the start of the Civil War, had the fear of violence loomed so large over a transfer of power.

Two blocks from the Capitol, a mother pushed a stroller up to the police tape, turned it around and posed her masked 1-year-old and 4-year-old for a photo.

“Say, ‘One, two, three, President Biden!’ ” Varina Winder told them, but her son, Theodore, was distracted.

“What are all those Army guys?” he asked. “What are they doing?”

“Um, they are supposed to protect the Capitol,” she said. “From the terrorists.”

Her son nodded, and she tried to think of what else to say. For four years, Winder, 36, had found herself trying over and over to come up with the right words to tell her children. When Theodore was 3, she had to assure him that while, yes, children at the border were being kept in cages, no, Trump wasn’t going to take him away, too. She took him downtown to Black Lives Matter Plaza this summer and tried to explain White privilege in a way he would understand. Then, two weeks ago, she had to explain that “terrorists” were people with “hate in their heart” who want to destroy things.

But Wednesday, she turned on the TV to watch Trump depart the White House. She dressed Theodore in a “Biden-Harris” shirt and made sure, once again, that he could pronounce “Kamala” the right way. She laughed when she heard her preschooler declare, “Trump is going back to Florida!”

Now Theodore had another question.

“Those guys,” he said. “Good police guys or bad police guys?”

Even with downtown D.C. in lockdown, the draw of such a historic day had brought people from all over the country who, in many cases, just wanted to say they were in the capital when Trump’s term ended and Biden’s tenure began.

Lydia Martinez brought her two sons, ages 13 and 15, more than 2,000 miles from their home in Fresno, Calif., even though she knew they probably wouldn’t see anything. Abel Perea, who had flown in from Kansas, woke up at 5 a.m., walked 17,000 steps and tried a dozen different security checkpoints before he found a spot along Pennsylvania Avenue, where he decided to wait, no matter how long it took, for a chance to see the new president pass by. Hoping that he could find a view of the swearing-in, Rick Duncan, a Democrat from deep-red Alabama, spent $2,200 for a D.C. hotel room — which is where he ended up celebrating, a bottle of vodka in hand.

Visitors and D.C., residents found ways to celebrate the inauguration of President Joe Biden and Vice President Kamala Harris under a security lockdown. (The Washington Post)

Gi Chung wished more of them could have come.

His family has peddled political souvenirs in downtown D.C. for nearly 40 years. Before this inauguration, he started his workday at 4 a.m. but didn’t meet his first customer for three more hours, when a student from American University bought a ribbon for $5.

In a typical inauguration week, Chung said, he sells $200,000 worth of merchandise, but by early afternoon, he’d sold only $1,000. Just before 2 p.m, he made the day’s biggest sale: $100 worth of T-shirts and pins commemorating the festivities.

The buyers, a family from Detroit, had taken a nearly empty plane and an equally empty train to reach Washington.

“It feels different today, like we have won the war,” said Earl Newsome, a 58-year-old military veteran who came to Washington with his wife and her sister.

To the south, closer to Pennsylvania Avenue, Samantha Pfeiffer’s mood was more subdued. She had come with friends from Michigan to celebrate, but the devastation from the pandemic and the ugliness of the attempted insurrection remained on their minds.

Like many at the inauguration, and across the country, they didn’t know quite what to feel. Her friend, Ralph Gaines, also 29, wasn’t expecting a quick turnaround in 2021, a year, he acknowledged, that was “probably not gonna be good.”

Pfeiffer was worried, too.

“He could have won, and that’s what’s sad,” she said, pointing to her mask as she thought about the virus. “If he hadn’t messed this up so bad, he could have won again.”

Jason Sheffield and Kiersten Dawley wished he had. The pair, from just outside Harrisburg, Pa., were among the few Trump supporters in town, the same place they had been on Jan. 6 when, they said, they watched a mob of fellow demonstrators storm the Capitol. Neither voted for Biden, but both said they wished him well.

“It’s supposed to be a time when America comes out. It’s part of the political process. But that’s not happening today,” said Sheffield, 36, motioning to the police barriers.

While they did not back Biden, both said they wanted the best for the country under his presidency, hoping he would not send more troops overseas or raise taxes.

“We have to hope for the best,” said Dawley, 22, just before she posed for a photo with a man holding an “Impeach 46” poster.

The divisiveness that consumed America for the past four years seemed far from the minds, or at least attitudes, of the two people at the center of Wednesday’s ceremonies. Not once in his speech did Biden disparage the people who voted for his opponent, whose name he never mentioned.

Along a crowdless parade route, military bands played and rows of troops wielded rifles and flags. As Biden’s motorcade approached the White House, he emerged from the limousine to walk the final few blocks.

He greeted people along the way, including D.C. Mayor Muriel E. Bowser and a few journalists.

“It’s been three hours,” “Today” show weatherman Al Roker shouted, just after Biden jogged over for a fist bump. “How does it feel, Mr. President?”

“It feels great,” Biden said.

He and his wife, Jill Biden, soon reached the White House grounds, their first time back since leaving office four years ago. With dusk approaching, they headed up the long driveway and, as the president stopped at the front door, a band played “Hail to the Chief.”

Then Biden hugged his wife, turned and walked into his new home.

Petula Dvorak, Meagan Flynn, Keith L. Alexander, Perry Stein, Katie Mettler, Michael E. Miller, Peter Jamison, Michael Brice-Saddler, Rebecca Tan, Michael E. Ruane, Justin Wm. Moyer, Harrison Smith, Marissa J. Lang, Marisa Iati, Meryl Kornfield, Laura Meckler, Justin George, Steve Thompson, Rachel Weiner, Luz Lazo, Hannah Natanson, Lola Fadulu, Lateshia Beachum, Samantha Schmidt, Julie Zauzmer, Moriah Balingit, Clarence Williams, Antonio Olivo, Paul Duggan, Kyle Swenson and Fredrick Kunkle contributed to this report.