BROWNSVILLE, Texas — When rail cars idle on side tracks in Mexico to be loaded with legitimate cargo and shipped to the United States, drug smugglers scan for places to hide their own loot — and if no good place is apparent, they make one.
Marijuana and cocaine can be concealed above rail car axles or behind false undercarriages made of plywood. Bolder smugglers sometimes weld a false wall into a car or sabotage trains to stop them and quickly stow their contraband on board before the train moves on. Cars are then tagged with graffiti or other markings so the dealer in the U.S. can spot his delivery.
Drug smuggling by rail "is something that for years may have gone under the radar," said Mayor Chad Foster of Eagle Pass, which is expected to become by next year the busiest rail crossing on the U.S.-Mexico border. Creative smugglers, he added, "don't miss a stroke."
Thousands of pounds of drugs arrive in the U.S. by freight train every year. Now the federal government says it's time American rail companies cracked down on their Mexican business partners to keep the drugs from reaching the border.
Drugs shipped by rail still represent only a fraction of the drugs seized along the border. But the volume of illicit cargo is growing in some places.
Last year, customs officers in Nogales, Ariz., seized more than 650 pounds of marijuana on three different trains in just one week.
In the previous six months, they had seized about 1 ton of marijuana, compared with only 367 pounds the year before. In Calexico, Calif., a particularly problematic crossing, 4 tons were seized between 2001 and 2006.
Smugglers have "been very opportunistic, and they have very good intelligence," said Scott Carns with Duos Technologies, a Florida company that has sold security systems to railroads and the government for use on the border.
Because American rail companies have an ownership stake in the two largest Mexican railroads, U.S. law enforcement is pressuring rail companies to crack down on smuggling.
If they do not comply, U.S. railroads risk massive fines. If the railroads improve security, trains could get quicker border inspections.
Earlier this year, the Justice Department sued Omaha, Neb.-based Union Pacific in three states to collect $37 million in fines for drug seizures made on its trains.
Armando Torres, a Mexican transportation consultant, said security by the railroads and Mexican law enforcement has been steadily improving since rail lines went private in 1997.
But drug smugglers still manage to move their shipments, and part of the problem is corruption, negligence or fear among rail workers, according to experts.
The U.S. government's approach to the problem is illustrated by the case of Union Pacific railroad and its Mexican partner, Ferrocarril Mexicano, or Ferromex, the largest railroad in Mexico.
Union Pacific, the busiest railroad 0crossing the U.S.-Mexico border, refused to pay the fines because it said it could not police rail cars before they enter the U.S.
Court documents suggest that the government really wants Union Pacific to use its 26 percent stake in Ferromex to pressure that company to improve security.
Last year, the U.S. government offered to cut one penalty against Union Pacific to 10 percent of the original $4.1 million, in exchange for cooperation and a promise that it specifically address drug smuggling on its railcars crossing the border at Calexico.
The same day the government sued Union Pacific, Ferromex issued a statement outlining its security investments.
The government's strategy appears to conform with its broader strategy of extending U.S.-style security measures south of the Rio Grande.
After the government sued, Union Pacific said it had "urged Ferromex to take action, but it views the Mexican military as having primary responsibility for drug interdiction in Mexico."
Union Pacific cannot be expected to achieve what neither the American nor Mexican governments could accomplish, "and it should not be punished," the railroad said.
Ferromex says it spent more than $15 million in 2008 on security measures, including fencing in rail yards, installing surveillance cameras and hiring drug-sniffing dog teams.
Ferromex spokeswoman Leonor Torres Duenas wrote in an e-mail that the company would take the same measures with or without U.S. pressure.
"Security is a constant concern for Ferromex, and we work to improve it because of the consequences it represents for our costs and the service we provide our clients, not for external pressures," Torres wrote.
Union Pacific says it has cooperated with Customs and Border Protection by donating border inspection buildings to the agency and providing K-9 training for government inspectors among other things.
Julian Bianchi, head of security services in Latin America for risk consultant Kroll Inc., said even the best security programs can be thwarted by "a person who can be influenced, bribed or threatened."