The market for illegal drugs globally is a multi-billion dollar enterprise, with profits flowing mainly to drug traffickers. In 2006, Mexico's President Felipe Calderon declared war on his own country's powerful cartels. As Mexican forces pursued them, rival gangs clashed over territory, and civilians were caught in the crossfire. Meanwhile, emboldened, cartels have expanded into Central America. As long as demand for drugs remains high, there's incentive to provide the supply.