The drug war between two rival gangs is having its effect on places tourists could once safely visit in Mexico.  Mexico City, with its national government, just a few days ago endured the grizzly scene of two headless bodies in a burning minivan, right in the parking lot of one of the city's most expensive shopping centers.  The once vacation attraction, Acapulco is now Mexico's second most violent city.   A University of San Diego expert on Mexican drug crime, David Shirk, told the New York Times, "There is a definite shift of violence away from the border and back to the inner states."  Violence along the border is down as Mexican military and police co-operate with American drug agents with helicopter patrols and remotely controlled drones.  Even Ciudad Juarez, the bloodiest city reports a decrease in the murder rate, but the border is not the place tourists go for extended relaxed vacations.  As the drug war between the Sinaloa and Los Zetas gangs moves South there are growing reports of extortion, kidnapping and killings in once safe areas, far from the drug routes.  Mexico estimates drug violence has killed 47-Thousand in the past 6 years, 7 times the deaths in Iraq since the beginning of the war in 2002.   Awful as it sounds, the true responsibility rests with Americans demanding Mexican and Colombian drugs.  With no demand, the cartels would dry up and be forced to search for more legitimate means of earning a living.