The Hanford History Project held the "Legacies of the Manhattan Project at 75 Years" conference in March 2017. Its Richland, Washington, meeting venue was a stone's throw from the southern-most edge of the Hanford Nuclear Site--the place where workers produced the plutonium that fueled the "Fat Man" nuclear bomb dropped on Nagasaki on August 9, 1945. The symposium's appeal extended well beyond local interest. Professionals from a broad array of backgrounds--working scientists, government employees, retired health physicists, downwinders, representatives from community groups, impassioned lay people, as well as scholars working in a host of different academic fields--attended and gave presentations. The diverse gathering, with its wide range of expertise, stimulated a genuinely remarkable exchange of ideas. In Legacies of the Manhattan Project, Hanford Histories series editor Michael Mays combines extensively revised essays first presented at the conference with newly commissioned research. Together, they provide a timely reevaluation of the Manhattan Project and its many complex repercussions, as well as some beneficial innovations. Covering topics from print journalism, activism, nuclear testing, and science and education to health physics, environmental cleanup, and kitsch, the compositions delve deep into familiar matters, but also illuminate historical crevices left unexplored by earlier generations of scholars. In the process, they demonstrate how the Manhattan Project lives on.