It was midway through her Saturday morning shift as Imane Parker, a clerk at the post office, stepped outside to find a line of protesters chanting and waving signs decorated like envelopes.

“Wow,” she said, visibly overcome for a moment. “This is so amazing.”

Parker had started the morning worn down after weeks of worrying about her customers experiencing delays in their mail deliveries. But now, she said, she felt glimmers of hope.

“We have your back!” one protester shouted.

Parker smiled beneath her mask and threw her fist in the air. The crowd cheered, and drivers slammed their horns, beginning a two-hour protest that would overtake a small street in Silver Spring, Md.

The protest was one of more than 800 community demonstrations at post offices that swept the nation Saturday as part of a day of action organized against controversial changes to mailing operations. Over the past few weeks, President Trump has concerned citizens and enraged Democrats by slowing mail service, blocking emergency funds and attempting to cast doubt on the integrity of mail-in ballots — all while acknowledging his intention to restrict how many Americans can vote by mail.

On Saturday, protesters in small towns and major cities across all fifty states lambasted Trump and called for Postmaster General Louis DeJoy, a Republican donor who took his post in June, to resign.

“What we are seeing is people respond because they rely on the mail, they need the mail and they care about the letter carriers and postal workers they see every day,” said Jenn Sturm, campaign director for MoveOn, an advocacy group that coordinated “Save the Post Office Saturday.”

In Frankfort, Ky., a line of spaced-apart protesters stood roadside with posters that read “Save the Post Office.” In Becket, Mass., a “small but mighty” group waved signs to “Save Our Election.” And in Portland, Ore., families and people on bikes rallied across an intersection in support of the Postal Service.

Catherine McGuffey, 59, stood waving American flags in front of the post office in Silver Spring, glad to feel like she was finally doing something after spending weeks glued to her phone. Even her husband had grown tired of her obsessive reading about the Postal Service. But she found it hard to think about anything else these days — especially when her 88-year-old father relies on the mail to receive prescription medicine and she had plans to vote by mail in November.

So when she heard about a protest in her neighborhood, McGuffey seized the opportunity, getting out poster board and bracing herself for one of her biggest public outings in more than five months.

“I am just so worried and so frustrated,” she said. “This is an American institution that is being torn down. I am here to push back.”

Anna White, 46, had organized more protests than she could count in her Maryland neighborhood. But she was shocked by how easily Saturday’s demonstration came together. After registering the event with MoveOn, she said, it spread through her community “like wildfire.”

As the Silver Spring demonstration stretched into early afternoon, protesters began to talk among themselves about their plans to vote in November. Many said they had initially hoped to vote by mail to avoid contracting the novel coronavirus at polling locations. But the recent chaos surrounding the Postal Service has given them pause.

“We really do need to be able to vote, and this feels like a deliberate attack on that right,” said Celeste Lucid-Weiser, 73, who has already applied for a mail-in ballot to avoid voting in a public location. She’s worried about catching the coronavirus and infecting her husband, who has a sensitive respiratory system.

Lucid-Weiser said she has started to reconsider her decision to vote by mail amid reports that the Postal Service is in a state of upheaval.

“I am afraid we are losing our democracy,” she said.

In addition to concerns about mail-in ballots and receiving prescription medications on time, protesters shared their personal relationships with the letter carriers in their neighborhoods. For White, her letter carrier reminds her of Valentine’s Day cards her kids sent to their grandparents.

“This protest is really a love letter for the Postal Service,” she said.

Miriam Torry-Coffidis, an 11-year-old who asked her father whether she could join him at the protest, wanted to defend the Postal Service for a slightly different reason. Ever since learning in school that people sent letters during the Revolutionary War, she has seen the Postal Service as central to American history.

“We just can’t forget about history,” she said. “Any president in the White House has to think about the reason they are there, and that is history, which is the Postal Service really.”

Philip Rucker, Josh Dawsey and Ashley Parker contributed to this report.