LOS ANGELES – More than 1 million mostly Hispanic immigrants and their supporters skipped work and took to the streets Monday in a nationwide boycott that succeeded in slowing or shutting many farms, factories, markets and restaurants.

A Day Without Immigrants, organized to raise awareness about immigrants’ economic power, attracted widespread participation despite divisions among activists over whether a boycott would send the right message to Washington lawmakers considering sweeping immigration reform.

“We are the backbone of what America is, legal or illegal, it doesn’t matter,” said Melanie Lugo, who with her husband and their third-grade daughter joined a rally in Denver. “We butter each other’s bread. They need us as much as we need them.”

Major rallies

Two major rallies in Los Angeles attracted an estimated 400,000, according to the mayor’s office. The city streets were a carpet of undulating white that stretched for several miles. In most cities across the country, those who rallied wore white to signify peace and solidarity.

Marchers holding U.S. flags aloft sang the national anthem in English as traditional Mexican dancers wove through the crowd.

In the Los Angeles area, restaurants and markets were dark and truckers avoided the nation’s largest shipping port. About one in three small businesses was closed downtown.

Police in Chicago estimated 400,000 people marched through the downtown business district.

One group of protesters in Chicago, huddled together against the cold, finally gave up trying to chant in Spanish and switched to their native Polish.

Nearby, gathered beneath an Irish flag snapping in the wind, members of the Chicago Celts for Immigration Reform cheered themselves hoarse. More than 100 students carried signs, written in Korean and Mandarin that read: “We Vote!”

Hispanic protesters slapped them high-fives and offered hugs.

Tens of thousands more marched in New York, along with about 15,000 in Houston, 50,000 in San Jose, Calif., and 30,000 more across Florida. In Denver, an estimated 75,000 people – more than one-sixth of the city’s population – marched through downtown.

In all, police departments in more than two dozen U.S. cities contacted gave crowd estimates that totaled about 1.1 million marchers.

Fire – and ice

The mood was jubilant. Marchers standing shoulder-to-shoulder filmed themselves on home video and families sang and chanted and danced in the streets wearing American flags as capes and bandanas.

In Phoenix, protesters formed a human chain in front of Wal-Mart and Home Depot stores. Protesters in Tijuana, Mexico, blocked vehicle traffic heading to San Diego at the world’s busiest border crossing.

Many carried signs in Spanish that translated to “We are America” and “Today we march, tomorrow we vote.” Others waved Mexican flags or wore hats and scarves from their native countries. Some chanted “USA” while others shouted slogans, such as “Si se puede!” Spanish for “Yes, it can be done!” Others were more irreverent, wearing T-shirts that read “I’m illegal. So what?”

The White House reacted coolly.

“The president is not a fan of boycotts,” said press secretary Scott McClellan. “People have the right to peacefully express their views, but the president wants to see comprehensive reform pass the Congress so that he can sign it into law.”

In Mexico, a daylong protest dubbed A Day Without Gringos drew thousands into the streets Monday and kept many away from U.S.-owned supermarkets and fast-food restaurants to support rallies in the United States.

Effect on business and schools

Industries in the U.S. that rely on immigrant workers were clearly affected, though the impact was not uniform.

Tyson Foods Inc., the world’s largest meat producer, shuttered about a dozen of its more than 100 plants and saw “higher-than-usual absenteeism” at others. Most of the closures were in states such as Iowa and Nebraska. Eight of 14 Perdue Farms chicken plants also closed for the day.

Goya Foods, which bills itself as the nation’s largest Hispanic-owned food chain, suspended delivery everywhere except Florida, saying it wanted to express solidarity with immigrants who are its primary customers.

None of the 175 seasonal laborers who normally work Mike Collins’ 500 acres of Vidalia onion fields in southeastern Georgia showed up.

The construction and nursery industries were among the hardest hit by the work stoppage in Florida.

“If I lose my job, it’s worth it,” said Jose Cruz, an immigrant from El Salvador who protested with several thousand others in the rural Florida city of Homestead rather than work his construction job. “It’s worth losing several jobs to get my papers.”

But the effect was minimal in some places. On Manhattan’s busy 14th Street, only a few shops were closed, including a Spanish-language bookstore and a tiny Latin American restaurant.

The effect on some school systems was significant. Officials from the Chicago Public Schools estimated that as many as one-third of the city’s 435,000 students didn’t show up for class.

In the sprawling Los Angeles Unified School District, which is 73 percent Hispanic, about 72,000 middle and high school students were absent – roughly one in every four.

In San Francisco, Benita Olmedo pulled her 11-year-old daughter and 7-year-old son from school.

“I want my children to know their mother is not a criminal,” said Olmedo, a nanny who came here illegally in 1986 from Mexico. “I want them to be as strong I am. This shows our strength.”