For Castulo Benavides, trade unionism that crosses national borders isn't just a pleasant slogan. It's what he does every day.

Benavides is in charge of the Monterrey, Mexico, office of the Farm Labor Organizing Committee ( FLOC ). That's the union of migrant agricultural workers who work with crops mainly in Ohio, Michigan and North Carolina ranging from cucumbers and tomatoes to cotton and Christmas trees.

Nearly all are from Mexico. Many regularly return home in winters. And since the lives of FLOC members are transnational, so is Benavides' job.

On one day, he investigates a North Carolina grower who's bypassing seniority rules in hiring. The next day, he files a grievance against a recruiter in Mexico trying to violate the FLOC contract and charge fees to a worker seeking a job. These recruiters can (and do) easily exploit migrant workers who aren't in FLOC—but in the case of a FLOC member, Benavides can force the recruiter to refund the money immediately.

Yet another critical job for Benavides is maintaining a network of FLOC workers in Mexico using small community meetings, phone contacts and foot traffic between villages that have no phone service.

Benavides' job also clearly has its risks. FLOC staff literally have been attacked for their efforts to help workers win a voice on the job. Benavides' co-worker, Santiago Rafael, was tortured and murdered in FLOC's Monterrey office last year—the killers have never been found—and the office has been the target of several break-ins and thefts of office equipment.

Yet Benavides is not deterred.

He knows just how important their union is for the migrant farm workers—because he was one for years. He's seen what it was like before FLOC, how hard it was for the workers to win their union, and how much they've gained once they had their union.

Before becoming part of FLOC, Benavides and others were victims of the corrupt system of recruiters. When he wanted to leave his home in the Mexican state of Tamaulipas to work in the fields of North Carolina, he says, "I had to pay about $600 to a recruiter just to get a job, so I could get a contract under H2A to come work in the United States. That was very common."

Under the H2A visa program for guest workers in agriculture, the employers have virtually complete freedom to hire and fire at will. Recruiters have free rein to charge workers outrageously high fees. Just to pay them, workers often have to go into debt for months or even years.

That was only the beginning. Once he came up north, Benavides found the living conditions for migrant agricultural workers were inhumane. "The housing was terrible," he recalls. "There weren't enough bathrooms and kitchens for all of us who were in the growers' housing camps. And we couldn't leave the farms because we didn't have any transportation. It was the same everywhere in North Carolina."

As for working conditions: "I remember one worker who got sick from the pesticides all around us," Benavides says. "He didn't get any medical care. The grower just sent him back to Mexico and told him to come back when he felt better. I saw other workers who got sick and were left under a tree until they died, like Raymundo Hernandez."

Benavides had little hope until he heard about FLOC from an organizer. He already knew about unions. He had briefly been a shop steward when he worked as a cashier at a Mexican credit union, so he signed on with FLOC and started talking to other workers in his camp about how a union could help them.

Before long, he became one of FLOC's organizers—but if organizing into unions is enormously difficult for most U.S. workers, it is even more difficult for migrant farm workers. "It was hard for us even to meet with the workers," he recalls. "The growers wouldn't let us enter the camps. Sometimes they forced us out at gunpoint or called the police or had us put in jail."

Workers also were scared of being sent back to Mexico." When we'd be talking with workers," Benavides adds, "many of them were showing an interest, but they were very, very afraid of getting involved or speaking about it to others."

Yet Benavides and the other workers in FLOC would not give up. They started organizing for a union in 1999. After five grueling years, which included a boycott of a North Carolina pickle manufacturer that was the cucumber growers' biggest customer, the workers won union recognition and their first contract.

Today, the difference for the workers is dramatic. "Now, they're paid by the hour and growers can't cheat them and say they've worked fewer hours than they've really worked," says Benavides. "The workers have water when they work in the fields."

He adds, "I knew a tobacco worker who was injured and lost a finger on the job. The union told him he could get workers' compensation. That never would have happened before. He would have gotten nothing."

And FLOC workers no longer have to pay anything to recruiters. Instead, under the collective bargaining agreement between FLOC and the employers, it is the employers who pay all the fees, even including those for processing visas.

Benavides is one of many union activists who are exploring new ways to work effectively across national borders, but the idea behind their work is as old as the union movement itself. "When workers are isolated and alone, they can't improve anything," Benavides says. "We have to be united to get fair working conditions. You have more power to make the changes you want."