As she watched Donald Trump’s helicopter lift away from the White House on Wednesday morning, Nadine Seiler said, she gave it the finger.

“I’ve been protesting him for four years,” the 55-year-old said. “I can exhale now that he’s gone.”

Seiler was standing in Black Lives Matter Plaza, outside the heavily barricaded White House, wearing an outfit that captured the arc of the last four years of protest. She had donned a pink knit pussy hat, a symbol of the Women’s March, the first major demonstration of Trump’s tenure, and a face mask painted with the words “Madam VP”, in honor of the country’s first Black, south Asian and female vice-president, who would be inaugurated later that day.

“I can’t let my guard down,” she added. “His supporters are going to be terrorizing America for the next four years.”

Even as he left Washington, Seiler said, Trump was “giving them dog whistles”, telling supporters their movement was not over.

Still, across an eerily quiet Washington, with streets blocked with fences and checkpoints, and 25,000 national guard troops – more than the number of US troops in Afghanistan and Iraq combined – on patrol, local residents said they felt tentatively hopeful.

“It’s like a weight being lifted off our chests,” said Jeni Stockman, who was pushing her infant son in a stroller in the street near the Cathedral of St Matthew the Apostle, when Joe Biden and members of Congress were attending mass.

At noon, as Biden was being sworn in, the streets near the White House were almost silent. Clusters of masked people stood together, watching Biden address the nation on their tiny cellphone screens. It was quiet except for the small echo of the new president’s voice: “Democracy is precious. Democracy is fragile … Democracy has prevailed.”

For a few minutes, Patricia Fobbs, 60, who had come to the inauguration from New Orleans, listened intently next to Isaiah Humes and Milion Cooper, both 20, who had driven 10 hours to Washington from Covington, Georgia.

Fobbs had made plans to attend the inauguration on the day Biden and Harris were elected, and had been “counting the days” ever since. On the day of the Capitol riot, “my spirit fell to the ground”, she said. But she had come to Washington anyway, despite her children’s fears about what might happen, to “see history in the making”.

The election of the first Black female vice-president was meaningful for her, at 60, but it meant even more for her children and grandchildren, she said. “It’s hope, that if we strive, we can be anything,” she said.

For the people who had made the Capitol look like “a war movie”, she said, and who had attacked Capitol police officers, “Every last one of them, including Trump, I want to see them go to jail.”

Stephen Spaulding, 38, wearing a sequined Biden-Harris face mask, said it was an “exciting day”, but that the mess Trump had left behind was “profound. And the cleanup needs to start on day one.”

In the barricaded, boarded-up Starbucks right outside the Capitol security perimeter, Camille Hynes was full of energy. The Starbucks executive was visiting employees who were keeping the store open, she said, to make sure that national guard members, journalists and Secret Service employees could get coffee in a mostly deserted city on a frigidly cold day.

Like Harris, Hynesis a graduate of Howard University, and a member of the Alpha Kappa Alpha sorority. She was wearing a pink and green “Madame Vice President” T-shirt in honor of Kamala Harris, as well as a multi-stranded pearl necklace.

“All the women who are recognizing this day in history are wearing pearls,” Hynes said.

Another Alpha Kappa Alpha sorority member, Crystal Miller, 47, had come to Washington from Dallas, Texas, to celebrate Harris’s inauguration. Her election represented “absolutely endless opportunity”, Miller said. For women and people of color around the world, who knew they could now follow in her footsteps, “It means everything,” she said.

Humes and Cooper, the Black college students who had driven to Washington from Georgia, said they voted for Democrats twice in Georgia, in the election and the runoff, making them part of a key segment of voters that had helped give the Democratic party control of both the White House and the Senate.

Cooper said he had helped knock on doors for the Democratic Senate candidates, even though he identifies as a Republican. Humes said he had been skeptical about whether his vote even mattered, in a country that so rarely seemed to value his life as a young Black man, but that he had cast his ballots anyway.

Now, both 20-year-olds were waiting to see if the Democrats would deliver enough change to earn their votes again. Police reform was one of their priorities.

“I don’t want my kids to feel the same way I do when I see a police officer,” Cooper said.

Someday, the two young men also wanted to tell their kids about their trip to a historic inauguration, although Cooper planned to change the story a little, from the reality of watching a cellphone video with strangers on a windy street. “I’m going to tell them that I was there, there,” he quipped.