NEW YORK — Thousands of people chanted, picketed and marched on cities across America on Monday as May Day demonstrations raged against President Trump’s immigration policies.

Protesters flooded streets in Chicago. They demanded “Donald Trump has got to go!” at the White House gates. And they sparked at least four arrests after creating a human chain to block a county building in Oakland, California, where demonstrators demanded that county law enforcement refuse to collaborate with federal immigration agents.

Despite the California clash, the initial rounds of nationwide protests were largely peaceful as immigrants, union members and their allies staged a series of strikes, boycotts and marches to highlight the contributions of immigrants in the United States.

“It is sad to see that now being an immigrant is equivalent to almost being a criminal,” said Mary Quezada, a 58-year-old North Carolina woman who joined those marching on Washington.

She offered a pointed message to Trump: “Stop bullying immigrants.”

The demonstrations on May Day, celebrated as International Workers’ Day, follow similar actions worldwide in which protesters from the Philippines to Paris demanded better working conditions.

But the widespread protests in the United States were aimed directly at the new Republican president, who has followed aggressive anti-immigrant rhetoric on the campaign trail with aggressive action in the White House.

Trump, in his first 100 days, has intensified immigration enforcement, including executive orders for a wall along the U.S.-Mexico border and a ban on travelers from six predominantly Muslim countries. The government has arrested thousands of immigrants in the country illegally and threatened to withhold funding from jurisdictions that limit cooperation between local and federal immigration authorities. The travel ban and sanctuary cities order were temporarily halted by legal challenges.

Trump has said his policies are meant to keep America safe.

In Chicago, 28-year-old Brenda Burciaga was among thousands of people who marched through the streets to push back against the new administration. “Everyone deserves dignity,” said Burciaga, whose mother is due to be deported after living in the U.S. for about 20 years. “I hope at least they listen. We are hardworking people.”

In cities large and small, the protests intensified throughout the day.

Teachers working without contracts opened the day by picketing outside schools in Philadelphia and Pittsburgh. Activists in Phoenix petitioned state legislators to support immigrant families. And in a Los Angeles park, several thousand people waved American flags and signs reading “love not hate.”

Selvin Martinez, an immigrant from Honduras with an American flag draped around his shoulders, took the day off from his job waxing casino floors to protest.

“We hope to get to be respected as people, because we are not animals, we are human beings,” said Martinez, who moved to Los Angeles 14 years ago fleeing violence in his country.