Here's a look at what you need to know about the Mexican Drug War. The Mexican government has been fighting a war with drug traffickers since December 2006. At the same time, drug cartels have fought each other for control of territory. More than 60,000 people have been killed.
Facts: There are approximated 6,700 licensed firearms dealers in the U.S. along the U.S.-Mexico border. There is only one legal firearms retailer in Mexico.
Nearly 70% of guns recovered from Mexican criminal activity from 2007 to 2011, and traced by the U.S. government, originated from sales in the United States.
90% of the cocaine that enters the U.S. transits through Mexico. Mexico is also a main supplier of marijuana and meth in the U.S.
Mexican drug cartels take in between $19 and $29 billion annually from U.S. drug sales.
Major Cartels: Beltran Leyva - Founded by the four Beltran Leyva brothers, Arturo, Carlos, Alfredo and Hector. Formerly aligned with the Sinaloa cartel, now aligned with Los Zetas against the Sinaloa, Gulf and La Familia Michoacana cartels. .
Gulf Cartel - Based in Matamoros, Tamaulipas. Formerly one of the most powerful cartels.
Juarez Cartel - Formerly aligned with the Sinaloa Cartel, now fighting it for control of Ciudad Juarez and the state of Chihuahua.
La Familia Michoacana - Based in the Michoacan state. Possibly defunct as of 2011.
Los Zetas Cartel - Comprised of former elite members of the Mexican military. Initially they worked as hit men for the Gulf Cartel, before becoming independent. They know battle the Gulf cartel for control of Tamaulipas and Nuevo Leon.
Sinaloa Cartel - Considered to be the dominant drug trafficking organization in Mexico. Led by Joaquin "El Chapo" Guzman.
Tijuana/Arellano Felix Cartel - Based in Tijuana. Most of the Arellano Felix brothers have been apprehended or killed.
Timeline: August 16, 2006 - Javier Arellano Felix, alleged head of the Tijuana cartel, is arrested on a fishing boat off the Baja peninsula.
December 11, 2006 - Newly elected Mexican president Felipe Calderon deploys more than 6,500 Mexican soldiers to the state of Michoacán to battle drug traffickers.
2006 - In the first few weeks of the government crackdown on drug trafficking, 62 people are killed. (Mexican government, April 2010)
January 2007 - Captured drug lord Osiel Cardena Guillen, alleged former head of the Gulf cartel, is extradited to the United States.
February 2007 - More than 20,000 Mexican soldiers and federal police are spread out across Mexico as part of President Calderon's drug war.
June 25, 2007 - Mexican president Felipe Calderon fires 284 federal police commanders to weed out corruption.
2007 - In the first full year of the drug war, 2,837 people are killed. (Mexican government, April 2010)
January 2008 - Alfredo Beltran Leyva, of the Beltran Leyva Cartel, is arrested by Mexican police in Culiacan, Sinaloa, Mexico.
May 1, 2008 - Roberto Velasco Bravo, Mexico's director of investigation for organized crime, is killed in Mexico City.
May 8, 2008 - Edgar Eusebio Millan Gomez, Mexico's federal police chief, and two bodyguards are killed in Mexico City.
May 9, 2008 - The commander of Mexico City's investigative police force, Esteban Roble Espinosa, is killed outside his home.
September 15, 2008 - During an independence day celebration in Morelia's town square, grenades are thrown into the crowd, killing eight people. The incident has been described as the first terrorist-style attack on innocent bystanders in Mexico's drug war.
November 1, 2008 - The acting head of Mexico's Federal Police, Victor Gerardo Garay, resigns under suspicion of corruption.