“I am fighting for my dad so he can get his papers,” Brian Chicaiza, a skinny sixth-grader with greased hair, said after leaving his Queens elementary school early yesterday to join the ribbon of protesters stretching up Broadway from City Hall to SoHo at one of the largest mobilizations for immigrant rights in city history.

The New York rally – like scores of coordinated marches across the country from small farming communities to the U.S. Capitol – gave a chance for America’s usually invisible workforce to voice its anger. At the demonstration, those who usually labor behind the scenes as delivery boys and demolition men, nannies and cleaning ladies, unified to demand that America not only accept their labor but afford them legal rights.

There were also thousands of children at the march, many of whom are American citizens with illegal immigrant parents, one of the many complex legal situations in a nation with 12 million illegal immigrants.

The New York turnout, estimated to be tens of thousands, did not rival those in Chicago and Los Angeles last month or one Dallas yesterday, each of which drew hundreds of thousands – but for many there it was a moving first venture into American civic involvement. Starting early in the afternoon and extending into the evening, protesters blocked traffic along Broadway and hoisted signs saying “Amnesty” and “We March Today, We Vote Tomorrow.” They waved and danced with flags from more than a dozen nations alongside the American flag and shouted “Si se puede,” or “Yes, we can.”

The march was organized by a broad coalition of immigrant organizations, church groups, and labor unions.

“We are here because this country has given us the opportunity to work,” Humberto Sandoval, 42, who delivers newspapers, said. He said he brought his family to America five years ago and then overstayed his tourist visa. Since then, he has been working illegally. Next to him at the march stood his 10-year-old daughter, Maria, who arrived when she was 6 and is also an illegal immigrant.

At her Queens elementary school, she said, illegal status is normal, but she said she was nervous about attending the march, because “right now Bush wants to throw all the immigrants out.”

More than 6% of New York City’s population, or 500,000 to 600,000 people, are illegal immigrants, according to estimates by the Pew Hispanic Center in Washington. In the past decade, Mexicans have been the fastest-growing major immigrant group in New York. They are approaching 25% of the city’s illegal immigrant population.

While there was undeniably a large presence of illegal immigrants at the peaceful march, no efforts were made to detain or deport them. The Mayor’s commissioner for immigrant affairs, Guillermo Linares, said it is city policy not to enforce immigration law, which is under federal jurisdiction. “We have half a million undocumented workers in this city,” he said. “We embrace them and we treat them the same way we treat everyone else.”

A spokesman for Immigration and Custom’s Enforcement, a division of the Department of Homeland Security, would not say if arrests had been made at the marches. The spokesman, Marc Raimondi, said the agency prioritizes “enforcement efforts to target criminal aliens that pose the greatest threat to national security and public safety.” Even the secretary of homeland security, Michael Chertoff, has said it is not feasible for the country to round up and deport all of the nation’s 12 million illegal immigrants.

As part of a solution to the nation’s broken immigration system, President Bush in January 2004 proposed principles for a new guest worker program, but Congress has been slow to follow with legislation. Last week, the Senate leadership of both parties declared a breakthrough that would have offered legalization to the majority of the nation’s illegal immigrants and temporary visas to the others if they first left America. The deal fell though, however, and even if the Senate renews it when it returns from Easter break, the likelihood of coming to an agreement with the House, which passed an enforcement-only bill last year, is unlikely.

At the march, Senators Schumer and Clinton joined other Democratic congressional representatives in stressing the need for the Senate to move forward with comprehensive immigration reform. “There are many in the Congress who want the bill in the Senate to go like the House,” Mr. Schumer said. “We will not let it happen no matter how long it takes.”