Thousands of people from all over the US have chanted, picketed and protested in demonstrations against Donald Trump's immigration policies, along with the traditional May Day labour march.
Protesters flooded streets in Chicago and at the White House gates, they demanded: "Donald Trump has got to go!"
In Portland, Oregon, police shut down a protest they said had become a riot as marchers began throwing smoke bombs and other objects at officers.
At least three people were arrested and police urged the rest of the protesters, who included families with young children, to leave after they withdrew the permit for the march.
In Oakland, California, at least four people were arrested after creating a human chain to block a county building where demonstrators demanded that law enforcement agencies refuse to collaborate with government immigration agents.
Despite the West Coast clashes, most nationwide protests were 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, 58, from North Carolina, who joined those marching on Washington.
And she offered a pointed message to President 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 anti-immigrant rhetoric on the campaign trail with aggressive action in the White House.
Mr Trump, in his first 100 days, has intensified immigration enforcement, including executive orders for a wall along the US-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 national immigration authorities.
In Chicago, Brenda Burciaga, 28, was among thousands of people who marched through the streets to push back against the new administration.
"Everyone deserves dignity," said Ms Burciaga, whose mother is due to be deported after living in the US for about 20 years.
"I hope at least they listen. We are hard-working 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 and activists in Phoenix petitioned state legislators to support immigrant families.
In a Los Angeles park, several thousand 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 Mr Martinez, who moved to Los Angeles 14 years ago, fleeing violence in his country.
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," he said at a Lansing, Michigan, rally.
"That's why I am here, to support not only myself but my entire community."
In Miami, Florida, Alberto and Maribel Resendiz closed their juice bar, losing an estimated revenue of 3,000 dollars, to join a rally.
"This is the day where people can see how much we contribute," said Mr Resendiz, who previously worked as a migrant worker in fields as far away as Michigan.
"This country will crumble down without us. We deserve a better treatment."
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.
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 US since massive demonstrations were held on that 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, but larger crowds returned this year, prompted by Mr Trump's presidency.