"Mexico is a major drug producing and transit country. Proceeds from the illicit drug trade leaving the United States are the principal source of funds laundered through the Mexican financial system. Other significant sources of illegal proceeds being laundered include corruption, kidnapping, extortion, piracy, human trafficking, and trafficking in firearms. Sophisticated and well-organized drug trafficking organizations based in Mexico take advantage of the extensive U.S.-Mexico border, the large flow of legitimate remittances, Mexico’s proximity to Central American countries, and the high volume of legal commerce to conceal transfers to Mexico. The smuggling of bulk shipments of U.S. currency into Mexico and the repatriation of the funds into the United States via couriers or armored vehicles, trade, and wire transfers remain favored methods for laundering drug proceeds. Though the combination of a sophisticated financial sector and a large cash-based informal sector complicates the problem, the 2010 implementation of U.S. dollar deposit restrictions reduced the amount of bulk cash repatriation back to the United States via the formal financial sector by approximately 70 percent, or $10 billion. According to U.S. authorities, drug trafficking organizations send between $19 and $29 billion annually to Mexico from the United States, though the Government of Mexico disputes this figure. Since 2002, Mexico has seized a total of more than $500 million in bulk currency shipments."

Source

"International Narcotics Control Strategy Report: Volume II, Money Laundering and Financial Crimes" (Washington, DC: US Dept. of State Bureau for International Narcotics and Law Enforcement Affairs, March 2014), pp. 161-162.
http://www.state.gov/document…