WASHINGTON — In protests fueled by anger over a tough anti-illegal immigrant law in Arizona, tens of thousands of demonstrators joined marches and rallies Saturday in cities across the country, calling on Congress to pass an immigration overhaul.
In Los Angeles, the police said the crowd had peaked at 50,000. Protesters numbered 25,000 in Dallas, more than 10,000 in Chicago and Milwaukee, in the thousands in San Francisco and here in Washington, D.C., according to the police and independent estimates. Organizers said rallies and vigils were held in more than 70 places around the country.
In Washington, Representative Luis V. Gutierrez, Democrat of Illinois, was arrested after staging a sit-in on the sidewalk in front of the White House with about three dozen other people, in front of a crowd of thousands.
At a rally before he was arrested, Mr. Gutierrez, speaking in English and in Spanish, evoked memories of the civil rights movement of the 1960s.
“There are moments in which you say, ‘We will escalate this struggle,’ ” he said. “Today they will put handcuffs on us. But one day we will be free at last in the country we love.”
In all, 35 people were arrested in the sit-in, the United States Park Police said.
At rally after rally across the nation, protesters chanted “shame, shame, Arizona,” and carried signs saying, “Todos Somos Arizona,” or “We are All Arizona.”
The bigger demonstrations were far larger than planners had anticipated in March, when the events were first announced. The protests were originally called by immigrant advocates who had set May 1 as the deadline for Congress to introduce overhaul legislation that would include measures to give legal status to millions of illegal immigrants.
But organizers said the Arizona legislation, which was signed into law April 23, had been a watershed event for disparate advocate organizations, transforming them into something akin to a civil rights movement with a national profile.