TIJUANA, BAJA CALIFORNIA, MX – JUNE 10 , 2009: Junkies with a tattoos, some of La Santa Muerte, hanging out on the ridge of the Rio Grande River basin on the the Tijuana side of the San Diego border region. It is common to see junkies in “picaderos,” or shooting galleries, shooting heroin along the border separating Mexico and the U.S., uninterrupted by nearby border patrol agents or Mexican police. Tijuana, a city of 1.3 million, has the highest prevalence of drug use in Mexico. The more than 2,000 mile border separating Mexico and the U.S forms the most extensive land frontier separating a developed and developing country. (Photo by Shaul Schwarz Reportage by Getty Images for National Geographic)
