While some critics of opening the border to Mexican trucks cite safety concerns, others are worried that it will lead to more drugs smuggled across the border in trucks.

The San Diego Union-Tribune Sunday looked at the issue in an article "Hidden Cargo: How Smugglers Goad, Bribe and Trick Trucking Businesses to Get Drugs Across the Border."
U.S. Customs Service officials told the paper they believe many drivers and companies caught with drugs in their shipments are unsuspecting participants. Drugs can be planted in cargo before or after a truck leaves a plant, or when trucks stop on the way to their destinations. Factory managers at U.S.-owned maquiladoras told the paper they or their drivers have been offered bribes to help them slip drugs into trucks heading into the United States.
Some smugglers even built secret compartments into trucks to hide drugs, or steal the identities of legitimate companies, according to the report. That's what apparently happened in the case of 1,700 pounds of marijuana found in a load of pinatas recently. Truck driver Jorge Retano says when a Tecate customs broker hired him to drive an empty trailer to Fontana, Calif., he questioned the broker about the job and even checked the trailer to make sure it was empty. But when he reached the border, drug-stiffing dogs discovered more than 3 tons of marijuana hidden in a secret compartment in the trailer's wall. His paperwork showed the owner of the pinatas was Ya Otta Pinata in Orange County, who said his company didn't own the pinatas.
U.S. officials say it's not easy to balance cracking down on drug trafficking with the need for speeding up truck traffic across the border. The number of customs officials at the Otay Mesa cargo area on the California border has dropped from 141 to 102 while the number of trucks crossing has more than doubled since 1995.
Nevertheless, the paper reports, the amount of marijuana seized in truck cargo at San Diego County's three border crossings increased by more than 6,400% from 1994 to 2000.