NPR recently published an article short on facts and long on conjecture concerning Mexican drug cartels thirst for American guns and America's craving for Mexican drugs.
The article here claims that the U.S. has little incentive to stop drug cartels from legally purchasing guns in the states and smuggling them over the border. But really, for someone to walk into a gun store and purchase a gun, they must submit a form 4473 and a background check is performed before the gun is allowed to leave the store. Further, the purchaser, in submitting to the background check, has fore sworn that this is not a straw purchase. So the statement that guns are being bought legally here and then smuggled over the border is a bit misleading. The guns are purchased here under a false pretense and smuggled into Mexico.
Of course, the ATF has problems tracing guns with the backlog at it's Martinsburg tracing center. On average it took two weeks to complete a request from Mexico. Also, the ATF no longer releases an estimate of how many straw purchases as it has become a political mess. Seeing as how the ATF will no longer release any hard numbers, the 90% of guns seized in Mexico can be traced back to the United States is even harder to believe. In fact, the correction is that of those guns seized and submitted, a much smaller number than the total, 90% of them came from the U.S. As of December 2008, Mexican Attorney General Eduardo Medina Mora put the number of recovered crime weapons in the country over the past two years at nearly 29,000, according to USA Today.
Of those nearly 29,000 guns 7,743 were submitted in 2008 and 3,312 in 2007.
Americas appetite for narcotics is insatiable. So long as Mexican cartels have a black market to supply, their wish to drive the competition out of business by violent means will prove equally rapacious. However, the problem is not one of America's Second Amendment being to blame for Mexican violence, it is Mexico's ineffectiveness in controlling it's own criminal element.