U.S. policies have helped create the cartels  A change in US immigration law in 1996 meant that non-citizens and foreign born citizens sentenced to more than a year in jail are deported. This moved the problem from the USA’s cities to cities in Central America creating new gangs that were already bound by ties created in the US. Effectively gangs created in the US thrived in central America where they were able to overwhelm the local government and spread north to Mexico and back into the USA helping create the network of gangs and drugs traffickers that plague Mexico today. [1] Similarly the problems in Mexico represent the success of the US in cutting of the routes through the Caribbean used previously by drugs traffickers. Colombian criminals as a result simply switched routes and began smuggling cocaine and heroin through the Central American isthmus and Pacific routes. Both smuggling routes led through Mexico. The successes of the war on drugs in Columbia has reduced the size of the drugs groups in Columbia reducing their ability to control the whole route to the USA making room for the Mexicans to take the role of middleman through Central America. [2]  [1] Wolfe, Adam, 'Central America's Street Gangs Are Drawn into the World of Geopolitics', Power and Interest News Report, 25th Aug. 2005.  [2] Logan, Samuel, ''Mexico's Internal Drug War'', Power and Interest News Report, 14th August 2006.