BRACING FOR MASS PROTESTS 500,000 EXPECTED TO RALLY IN L.A. FOR IMMIGRANT RIGHTS.

Byline: Staff and Wire Services

If Californians keep one thing in mind for today's "Day Without An Immigrant" it should be this: Be prepared for anything.

Some stores, restaurants and work sites will close - because workers don't show up or due to customers staying away as part of an economic boycott. Classrooms in some schools will be empty.

And if hundreds of thousands of illegal immigrants and their supporters do participate, rallies at government buildings statewide could swell. In Los Angeles, police are preparing for 500,000 marchers.

Hispanic activists claim widespread support for the boycott - an idea hatched in Southern California that has spread nationwide - despite calls by religious and union leaders that workers and students rally after work and school hours. Even limited participation could have a noticeable effect: One out of four Californians is foreign-born, and an estimated 30 percent of those immigrants are undocumented.

"We have heard everything across the board," said Jordan Traverso, spokeswoman for the California Restaurant Association. "Members who would like to stay open but know they can't, members worried that customers would see them being sympathetic to the cause, and ones who want to close because they are sympathetic."

Saying he expects today's marches and protest over U.S. immigration laws to be peaceful, Mayor Antonio Villaraigosa announced Sunday he had postponed a planned early-morning trip to Dallas to meet with NFL officials and will remain in the city during the massive protest.

At a rare, Sunday City Hall news conference, Villaraigosa appealed for calm from participants and all Angelenos.

"We expect the marches to be as peaceful as the one on March 25 when a half-million people turned out," Villaraigosa said.

But, he acknowledged, there will be disruptions - in the downtown area in the morning and around MacArthur Park in the afternoon - when the demonstrations are planned.

"If you have business in these areas, give yourself plenty of time and prepare to take alternate routes," Villaraigosa said.

The boycott is the crescendo to a wave of national protests over a bill passed by the House that would make it a crime to lend a hand to illegal immigrants and would build hundreds of miles of walls along the U.S.-Mexico border.

It comes as the Senate considers legislation to strengthen the nation's borders, expand temporary worker programs and give many of the 11 million illegal immigrants a chance at citizenship - the central demand of protesters.

While many immigrants will not participate, there is a feeling that today won't be like any other day. And business owners, parents and others are trying to prepare.

Dozens of day labor centers and businesses statewide have already announced plans to close. Parents are scrambling to make contingency plans if baby sitters don't show up, or if there are massive student walkouts.

Villaraigosa on Sunday renewed his call for students to remain in school during the day.

"If you feel strongly and want to demonstrate, you can do so in the afternoon," Villaraigosa said. "Your primary responsibility is to be in school."

The mayor also said he expected all city workers to be on the job.

A Port of Long Beach spokesman said he's heard hundreds or even thousands of truckers may not show up to haul cargo to or from the waterfront.

On Friday, a handful of Hispanic truckers called for a general strike and urged truckers statewide to follow.

"We need to change this country," said trucker Rodolfo Pinera, a Salvadoran immigrant.

"This country is about to meet the giant who was sleeping."

Los Angeles-based La Curacao, a major retailer catering to Hispanic clients, will keep stores open today, but only to provide information on immigration reform.

The decision came after numerous customers expressed how important the boycott was to them, while many employees didn't want to lose a day's pay, said Mauricio Fux, vice president for corporate development.

"We'll lose hundreds of thousands of dollars, but you can't force people to do one thing or the other," said Fux.

Demonstrations are planned from Fresno to San Diego, including a noon rally at the state Capitol. Some are planned for work and school hours, with others scheduled to take place afterward.

Police in Los Angeles are planning for two rallies they believe could muster a half-million people - similar to the March 25 protest viewed as a formative moment in the movement.

Authorities have said they're not expecting violence, and plans for counter protests are notably absent.

While some Hispanic activists are calling for employees to stop work and students to skip school, other proponents of immigration reform, including more moderate Hispanic groups, the Catholic Church, and national labor unions, are encouraging immigrants to demonstrate after work and school.

The different times of the two Los Angeles rallies - one planned for noon and the other at 4 p.m. - are a manifestation of that division and suggest why Monday could either be historic or just one of many protest days.