“The kind of multigenerational drug use he was describing was not uncommon in their town, Austin, in southern Indiana. It’s a tiny place, covering just two and a half square miles of the sliver of land that comprises Scott County. An incredible proportion of its 4,100 population—up to an estimated 500 people—are shooting up. It was here, starting in December 2014, that the single largest HIV outbreak in U.S. history took place. Austin went from having no more than three cases per year to 180 in 2015, a prevalence rate close to that seen in sub-Saharan Africa.”