The Associated Press

ALTAR, Son. - A year after a spectacular police crackdown on migrant trafficking in this town not far from the U.S.-Mexico border, the plaza bustles with smugglers closing deals.
The United States has urged Mexico to crack down harder, warning that terrorists could tap into the flourishing industry. But Mexico says it can do little at the northern border because, although aiding illegal crossings for a fee is a crime, there's no law to stop would-be migrants from gathering near the border.

Instead, Mexico appears to have focused on stopping the flow of U.S.-bound migrants from South and Central America at its southern border. In March, police carried out a nationwide sweep against one of the largest migrant-trafficking rings ever uncovered in Mexico.

It netted 42 current and former government employees in 12 of Mexico's 31 states who allegedly smuggled Cubans, Uruguayans, Brazilians, Asians and Central Americans across Mexico's southern border.

Mexican officials said corrupt officials illegally freed captured migrants, falsified documents to get them through Mexico and guaranteed them safe passage into the United States.

The raid at Altar, a town of 7,000 about 60 miles south of Arizona, caught 27 suspects and rounded up about 60 Central Americans for deportation. Hundreds of Mexican migrants were encouraged to return home, and Interior Secretary Santiago Creel promised more raids would follow.

Yet Altar remains the busiest crossing point along the northern border, and trafficking apparently goes on undisturbed.

Boarding houses are almost always full, and many farmers have abandoned their fields and opened restaurants and shops that cater to the transient population.

Last year's arrests were "a complete spectacle," said Francisco Garcia, Altar's mayor at the time. "But as far as I'm concerned, they didn't have any effect because here things remain the same."

Garcia said the raids were just a symbolic response to U.S. pressure, coming two weeks after 19 migrants died of heat and asphyxiation while being smuggled to Houston in a tractor-trailer rig.

Visiting Mexico in February, Homeland Security Secretary Tom Ridge asked Mexico to step up patrols along its border with the United States, saying doing so would help head off terrorism.

In an agreement signed at the time, Mexico pledged to crack down on migrant smugglers.

But breaking up smuggling rings has proven difficult.

Mexico's Interior Department estimates that as many as 100 smuggling gangs operate across Mexico, charging up to $1,800 per migrant.

Jose Luis Santiago Vasconcelos, Mexico's chief prosecutor in charge of organized crime investigations, said corrupt officials are one of the main roadblocks.

They "stain our country's reputation, and as a result our efforts seem to evaporate," Vasconcelos said. "Everyone is making a great effort to stop this type of activity."

Luis Sanchez, a 30-year-old farmer from southern Oaxaca state, said he has crossed illegally into the United States four times. "We always cross through Altar because here no one bothers you," he said.