The John H. Powell papers include approximately three linear feet of material and consist primarily of correspondence and material involved with his various writings. The correspondence series includes letters from historians such as Catherine Drinker Bowen, Julian Boyd, Lyman Butterfield, and Caroline Robbins. The writings series includes notes and various drafts of his works and two unpublished plays. The American Philosophical Society Library also has a collection of John H. Powell's papers, primarily those concerning Powell's biography of John Dickinson.