Heroin smugglers in Central Asia are saying “Thanks, America!” for the $37 million bridge built by the U.S. Army Corps of Engineers in 2007. Intended to help expand trade between poverty-stricken Afghanistan and Tajikistan, the bridge across the Panj River has turned out to be a boon for drug smugglers. Prior to the construction of the concrete span, traffickers were limited to crossing the Panj using makeshift bridges, which greatly limited the flow of heroin across the border. But now opium shipments roll by the truckload into Tajikistan, helping expand the burgeoning flow of drugs across Afghanistan’s northern route. According to United Nations figures, an average of more than four metric tons of opium were transported every day last year through that route, which is enough raw product to produce nearly six million doses of pure heroin for the street trade in Europe.