NEW YORK -- Thousands of people from New England to the Midwest to the Southwest chanted, picketed and protested Monday as demonstrations raged against President Donald Trump's immigration policies along with the traditional May Day marching in favour of labour.

Protesters flooded streets in Chicago.

At the White House gates, they demanded "Donald Trump has got to go!"

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 travellers 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 co-operation between local and federal immigration authorities.

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 set 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.

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.

The White House did not respond to requests for a response to the May Day demonstrations.

Several protesters, like 39-year-old Mario Quintero, outed themselves as being in the country illegally to help make their point.

"I'm an undocumented immigrant, so I suffer in my own experience with my family," said Quintero at a Lansing, Michigan, rally. "That's why I am here, to support not only myself but my entire community."

In Miami, Alberto and Maribel Resendiz closed their juice bar, losing an estimated revenue of $3,000, to join a rally.

"This is the day where people can see how much we contribute," said Alberto Resendiz, who previously worked as a migrant worker in fields as far away as Michigan. "This country will crumble down without us."

He added, "We deserve a better treatment."

In Portland, Oregon, about 200 people including families with children and dancers in bright, feathered headdresses performing to drums, took part in the protests.

Several dozen people dressed entirely in black and wearing black bandanas and ski masks on their faces stood around the fringes of the gathering holding signs that read "Radicals for Science!" and "No cuts! Tax the rich!" as police officers looked on.

In Providence, Rhode Island, about the same number of people gathered at Burnside Park before a two-hour protest that touched on deportation, profiling and wage theft.

More rallies are planned later Monday, including in Las Vegas and San Francisco.

While union members traditionally march on May 1 for workers' rights around the world, the day has become a rallying point for immigrants in the U.S. since massive demonstrations were held on the date in 2006 against a proposed immigration enforcement bill.

In recent years, immigrant rights protests shrank as groups diverged and shifted their focus on voter registration and lobbying. Larger crowds returned this year, prompted by Trump's ascension to the presidency.

------

Taxin reported from Los Angeles. AP writers Jessica Gresko in Washington, D.C., Kristen De Groot in Philadelphia, Adriana Gomez Licon in Miami, Sophia Tareen in Chicago, Deepti Hajela in New York, Sarah Rankin in Richmond, Virginia, Lisa Adams in Charlotte, North Carolina, Gillian Flaccus in Portland, Oregon and Crystal Hill in Providence, Rhode Island contributed to this report.