Oral history interviews with Harry Mortenson conducted by Claytee D. White on April 08, 2014, April 22, 2014, and May 06, 2014 for the Boyer Early Las Vegas Oral History Project. In the first interview, Mortenson discusses his personal background, working at Los Alamos National Laboratory in New Mexico, and arriving to Nevada to work as a nuclear physicist at the Nevada Test Site. Mortenson describes his work and recalls anecdotes from his employment. He then talks about his company, Sigma Scientific, and explains the different projects where he worked as a consultant. In the second interview, Mortenson discusses the methods of transportation used to arrive to the Nevada Test Site, his involvement with different organizations, and his tenure in the Nevada State Legislature. In the final interview, Mortenson discusses the device he built to take photographs of the nuclear reactor cores at Las Alamos National Laboratory, and explains how that device worked.