EL PASO, Texas | U.S. authorities say that as attention increases on gunrunning between Mexico and the United States along the border, the illegal trade is emanating from deeper in the United States.
"We're finding guns aren't just coming from [the] Southwest border," said William McMahon, deputy assistant director for field operations at the Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF). "We're seeing hot spots farther north and east, too."
In 2007, guns recovered in Mexico were traced back to states including Florida, Georgia, South Carolina and Washington state, he said. Cartels are using long-established drug-smuggling routes that extend deep into the United States to secure and move weapons south, Mr. McMahon said.
Still, "the majority are from the state of Texas" and other border states, said Tom Crowley, ATF special agent and spokesman at the Dallas field division.
U.S. officials estimate that 90 percent to 95 percent of guns smuggled into Mexico come from the United States, and ATF officials say that more than 7,700 weapons recovered in Mexico last year were traced to U.S. gun sellers.
The Mexican government estimates that 2,000 firearms are smuggled into the country from the United States every day.
Generally, drug traffickers don't move cash and drugs together, Mr. McMahon said. Cash is a bulky commodity that takes greater resources to move, so drugs are frequently traded for caches of weapons, he said.
Sen. Richard J. Durbin, Illinois Democrat, told a Senate hearing on March 18 that the U.S. and Mexico are connected by what he described as an "iron river of guns."
The Washington Times reported last month that senior U.S. defense officials estimate that the Mexican drug cartels together field more than 100,000 foot soldiers. The narco-armies are equipped with light weapons, mostly rifles and pistols obtained through the illegal gun trade.
Firefights between cartel members and Mexican government troops often resemble guerrilla war-style engagements. While heavier armaments such as fragmentation grenades and grenade launchers - shipped primarily by sea or through the porous Mexico-Guatemala border - are becoming increasingly commonplace, the United States is still the prime source for firearms, ATF officials say.
The trade persists despite enforcement efforts.
ATF has tripled its staff along the border under Project Gunrunner, instituted in 2006 to help stem the flow of firearms from the U.S. to Mexico. Currently, about 200 ATF agents police more than 6,500 licensed firearms dealers in the border states.
"The agents here are working 24/7," Mr. Crowley said.
Firearms make their way into the hands of smugglers from "straw man" purchasers, he said.
A straw man is someone with a clean record who buys firearms from gun shops or gun shows with money furnished by criminals. The straw man then hands over the weapons, which are smuggled into Mexico.
Straw-man purchasers have no standard profile, Mr. Crowley said, making it difficult for firearms dealers to identify such individuals. "They could be anybody. We have men, women, older people. It runs the gamut," he said.
Emerson Gates, gunsmith at Custom Cartridge Co. in Las Cruces, N.M., 30 miles from the U.S.-Mexico border, says gun dealers are "the last line of defense" against the illegal firearms trade.
Though a buyer might conform to federal guidelines, the dealer has the final say. If the buyer raises suspicion, for any reason, it's the responsibility of the firearm salesman to reject the sale.
"Sometimes, we do this with what's known as an in-store delay," Mr. Gates said. "Other times, we simply refuse."
A common straw-man purchase scenario might involve a young woman who clearly has no interest in firearms, accompanied by a man of "unsavory" appearance, Mr. Gates said.
She's buying the firearm, but the money is coming out of his pocket. "We inform them at that time that we cannot sell to them under these circumstances, because it would be a felony for them and a felony for us," Mr. Gates said. "And I'm extremely allergic to federal prison."
Firearms dealers are occasionally indicted for working directly with drug cartels. That was the case of a Phoenix-based owner of X-Caliber guns, George Iknadosian, who provided hundreds of AK-47 assault rifles to the Sinaloa cartel, prosecutors say.
However, Mr. Gates said that was the exception rather than the rule. "Generally speaking, we work in fairly close concert with the ATF," he said. "We don't want to see illegal firearms or ammunition going to Mexico."