Demonstrators rallied across the nation on May Day to demand an overhaul of immigration laws. The annual ritual carried a special sense of urgency as Congress considers sweeping legislation that would bring many of the estimated 11 million people living in the U.S. illegally out of the shadows.

In New York, paper rats on sticks bobbed along Sixth Avenue as about 200 protesters set off from Bryant Park, chanting: "What do we want? Justice! When do we want it? Now!" The rats were intended to symbolize abused migrant workers.

May Day rallies were planned in dozens of other cities from Tampa, Fla., to Bozeman, Mont. At a rally in Salem, Ore., Gov. John Kitzhaber planned to sign legislation to authorize drivers' licenses for people living in the state without documentation.

"The invisible become visible on May 1," said Angelica Salas, executive director of the Coalition for Humane Immigrant Rights of Los Angeles, which organized what was expected to be the nation's largest rally.

The crowds were not expected to approach the massive demonstrations of 2006 and 2007, during the last serious attempt to introduce major changes to the U.S. immigration system. Despite the large turnouts, many advocates of looser immigration laws felt they were outmaneuvered by opponents who flooded congressional offices with phone calls and faxes at the behest of conservative talk-radio hosts.

Now, immigrant advocacy groups are focusing heavily on calling and writing members of Congress, using social media and other technology to target specific lawmakers. Reform Immigration for America, a network of groups, claims more than 1.2 million subscribers, including recipients of text messages and Facebook followers.

A phone blitz targeting Republican U.S. Sen. Orrin Hatch produced 100 calls a day to the Utah lawmaker's office last week, said Jeff Parcher, communications director for the Center for Community Change, which works on technology-driven advocacy for the network of groups. After Hatch was quoted Sunday in The Salt Lake Tribune saying immigration reform couldn't wait, a message went out to call his office with thanks.

Gabriel Villalobos, a Spanish-language talk radio host in Phoenix, said many of his callers believe it is the wrong time for marches, fearful that that any unrest could sour public opinion on immigration reform. Those callers advocate instead for a low-key approach of calling members of Congress.

"The mood is much calmer," said Villalobos, who thinks the marches are still an important show of political force.

Salas, whose group is known as CHIRLA, dates the May Day rallies to a labor dispute with a restaurant in the city's Koreatown neighborhood that drew several hundred demonstrators in 2000. Crowds grew each year until the House of Representatives passed a tough bill against illegal immigration, sparking a wave of enormous, angry protests from coast to coast in 2006.

The rallies, which coincide with Labor Day in many countries outside the U.S., often have big showings from labor leaders and elected officials.

The New York crowd was a varied bunch of labor groups, immigrant activists and demonstrators unaffiliated with any specific cause. Among them was 26-year-old Becky Wartell, who was carrying a tall puppet of the Statue of Liberty.

"Every May Day, more groups that have historically considered themselves separate from one another come together," she said.

Based on reporting by The Associated Press.

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