The traditional celebrations of the labor movement took on an added urgency as the U.S. Congress considers legislation that could provide a path to citizenship for many of the 11 million people living illegally in the United States.
An estimated 30,000 labor and immigrants' rights advocates congregated in downtown Los Angeles waving the flags of the United States and other countries as they marched to mark International Workers' Day, NBC-TV, San Francisco, reported.
Crowds were large but calm in Los Angeles, which experienced moderate traffic problems.
"It's a very peaceful crowd. A lot of different groups have come together to both celebrate and protest. So far it's gone very well," LAPD Cmdr. Andrew Smith told the Los Angeles Times.
Oregon Gov. John Kitzhaber joined a crowd of thousands on the Capitol steps in Salem to sign a bill allowing undocumented individuals to obtain drivers' licenses. Similar scenes unfolded at statehouses across the country.
In New York City, protesters marched down Sixth Avenue chanting, "What do we want? Justice! When do we want it? Now!"
Demonstrators braved cold, wind and snow across the country's midsection. In Denver, undocumented 26-year-old Naykary Silva said she wants Congress to pass legislation that would help her 3-year-old autistic son gain access to medical care.
"If you want to do something, you do it no matter what," Silva said. "There's still more work to do."
Seattle police were out in full force to discourage any violence, and some banks announced they would close early as a precaution, KOMO-TV, Seattle, said.
Hundreds of demonstrators marched through downtown Chicago beginning at 2 p.m., with some minor skirmishes reported.
"Today people are just marching around the Loop and downtown," Occupy Chicago spokeswoman Rachael Perrotta told WLS-TV, Chicago. "It's a celebratory day. We did have one arrest earlier on Michigan Avenue as the cops were sort of violently moving people out of the streets and onto the sidewalk."
Many protesters called for the end of deportations.
"We are workers. We are parents. We won't stop fighting until these deportations end," Rosie Carrasco, an activist on Chicago's Southwest Side, told the Chicago Tribune.