BOSTON — Sierra Rothberg awoke on Monday to a battered city.
Venturing into downtown Boston at 6:30 a.m., she saw red and black graffiti scrawled on the walls of the State House. Restaurants and shops gaped open to the street, their windows smashed. Mailboxes were overturned. The tall grass of Boston Common was littered with broken glass, looted shoes and discarded signs.
Worse than all of these was her feeling of sadness that a protest that had inspired her had ended with destruction.
So Ms. Rothberg, 45, did what she often does when faced with a problem. She started gathering together cleaning supplies.
By 9 a.m., she was out on the sidewalk, sweeping debris into a small dustbin.
“I thought, ‘I’m a doer, I need to get my hands in there,’ ” said Ms. Rothberg, an event planner. By early afternoon, more than 100 people had joined her, some in response to her Facebook callout and some spontaneously.
“They would say, ‘Can I help? I have 15 minutes,’ and they would stay for three hours,” Ms. Rothberg said. “People could not give up on it. It took on a life of its own. A guy jumped out of his jeep and brought us 10 pizzas.”
A hallmark of recent days in America is that, in cities troubled by contagion, grief and now violence, people are coming out of the woodwork to clean.
Residents of Los Angeles, a city sometimes said to lack a civic fabric, were out with glass cleaner and long-handled brooms. Volunteers scrubbed the walls of the State Capitol in Denver, swept up the shattered windows of stores in Fargo, N.D., and repaired damaged buildings in downtown San Antonio.
In San Jose, Calif., on Monday, Mayor Sam Liccardo was handing out cleaning kits — a bucket, a scraper, some rags and Goo Gone, a chemical solvent — and offering a short course in graffiti removal.
“You end up having to scrub — a lot,” he said. He called the cleanup “an ongoing task,” and said that not all of the protesters were “doing so in true community spirit.” Several dozen small businesses in San Jose had their windows smashed in protests over the weekend.
“It tears your heart out,” he said, “because they are struggling so much already.”
In interviews, organizers of cleanup events said they were motivated, in part, by fear that the protests would come to be defined by looting and vandalism.
“So many people were worried that the message was getting lost in the violence,” said Justine Sandoval, 34, the president of the Denver Young Democrats, who organized a cleanup event on Sunday in Denver.
“They want to show up and say, ‘These protests are important, but we’re going to be there to pick up the pieces afterward,’ ” she said. “It felt good, because we want to keep this conversation going.”
She said local politicians were quick to latch onto the cleanups, perhaps seeing them as a sign of conciliation — but that, she said, was a misunderstanding.
“It still doesn’t erase the fact that we’re fighting, because black people are being killed by the police in this country,” she said.
Some who cleaned up said it helped calm them after days of intense emotion.
“I thought, ‘OK, I’m back at the peaceful part of it,’ ” said Rachel Madden, 55, who, along with her sisters, spent part of the weekend picking up garbage on Lake Street in Minneapolis.
Ms. Madden, who is white, said she could understand the rage that led to looting and vandalism, and that she might do the same if she had grown up black in those neighborhoods.
“I feel like buildings need to burn, sadly, for people to listen,” said Ms. Madden, an artist. “And then I’m happy to come and clean up and do what I can.”
In Boston, the cleanup began at around 3 a.m., when the city’s public works department deployed 12 street sweepers. At 4 a.m., they were joined by sidewalk sweepers — not machines, but humans with brooms. At 6 a.m. the city sent the team of workers who specialize in graffiti removal.
Much of the work was finished by 9 a.m., a city official said.
It was nearly 10 by the time Audrey Markoff, an artist, and her husband biked to the Common, surveying smashed storefronts along the way.
It made them sad; they had watched the protests with sympathy, and did not expect violence on Sunday. “I thought Boston was going to be the peaceful one,” said her husband, Greg Dunn.
They wanted to help clean, in part to show that the violence was not representative of all of the protesters.
“There was a huge turnout this morning from the protest people, because they’re separate from the riot people,” said Ms. Markoff, 33. “They’re illustrating that these are separate groups of people, separate events.”
By they time they reached the Common, though, much of the cleaning had already been done, and there were plenty of volunteers already. Ms. Markoff left relieved at how quickly the city had responded. “I hope it doesn’t happen again tonight or tomorrow,” she said.
If it does, Ms. Rothberg said, she would organize another cleanup. Already, she is coordinating with the Parks Department to clean up after a rally planned for Tuesday.
“There was so much unrest and uncertainty and scary feelings,” she said. “What I really found is that the most beautiful moments were the aftermath — that people were coming together and saying, ‘Oh, come on, this doesn’t represent us.’”
John Eligon contributed reporting from Minneapolis, Jennifer Medina from Los Angeles and Thomas Fuller from San Francisco.