Methamphetamines and marijuana are grown or manufactured in Mexico itself while heroin and cocaine are shipped through that country to the United States. In the former two categories, Mexico is the top foreign supplier for U.S. consumption. Mexico accounts for only a small share of worldwide heroin production, but the State Department estimates that 90% of cocaine entering the United States is moved through Mexico. In 2006, the United States, wholesale illicit drug sale earnings estimates range from $13.6 to $48.4 billion annually.

The Mexican drug cartels are not new but since the removal of the Medellin and Cali Columbian cartels, have become dominant in the American drug trade When the U.S. agencies succeeded in shutting down the Florida cocaine traffic, it then moved to Mexico. The official view, though unpublished , is that Mexico now dominates all drug imports into the United States. This subject is not openly explored because it threatens the pipeline of cheap labor still flooding over the border, bringing with it the drug traffickers and the hard-core criminals who settle in the border cities and in LA to organize their branch offices. Even if drugs were suddenly legalized, these guys would still do business the same way.

Further, in addition to smuggling tons of drugs into the United States, Mexican cartels are the leading wholesale launderers of drug money from the United States. Mexican and Colombian trafficking organizations annually smuggle an estimated $8.3 to $24.9 billion in drug proceeds into Mexico for laundering.

Mexican cartels also produce methamphetamine and marijuana in the United States. Mexican cartels have long grown marijuana in the United States, often on federal land in California, but they are now expanding production to the Pacific northwest and, to a lesser extent, the eastern United States. Mexican marijuana producers in California, the Pacific northwest, and eastern United States are increasingly linked to each other and "[m]any of these groups maintain their affiliation with the larger groups in California and Mexico and maintain some level of coordination and cooperation among their various operating areas, moving labor and materials to the various sites – even across the country – as needed."

Mexican street gangs such as the Mara Salvatrucha and the Latin Kinds purchase drugs from the Mexican drug cartels for distribution in the southwestern United States. According to the FBI, Mexican cartels focus only on wholesale distribution, leaving retail salesof illicit drugs to street gangs. In addition to drug trafficking, Mexican cartels have been tied to both human and arms trafficking, auto theft, and kidnapping. Mexican drug traffickers increasingly smuggle money back into Mexico in cars and trucks, likely due to the effectiveness of U.S. efforts at monitoring electronic money transfers, mostly via Western Union..."