AP Photo

In September 2012, Michael Rhodes, a technician at the National Declassification Center (NDC) in College Park, Md., donned white cotton gloves, entered a climate-controlled room, and opened a cardboard file box. It was time for the report inside—"Project 1794 Final Development Summary Report 2 April—30 May 1956"—to become public. Rhodes's job is to read such documents, catalog them, and make them available to historians, journalists, and the curious. The paper was crisp, like new. Rhodes began to read.