McDonald Ranch at Trinity Site
The George McDonald Ranch House, located west of the Oscura Mountains on the White Sands Missile Range, was the site of the final assembly of the plutonium core for the world's first atomic bomb. Code-named "Fat Man", the bomb was detonated on July 16, 1945, at Trinity Site, approximately two miles north-northwest of the ranch house. Members of the nuclear assembly team, led by Robert Bacher and Marshall Holloway and assisted by Louis Slotin, assembled the core components on July 13 in the northeast room of the ranch house. Others present included Brigadier General Thomas Farrell, deputy director of the Manhattan Project; Doctor J. Robert Oppenheimer, director of Los Alamos Scientific Laboratory, and Commander Norris Bradbury, who directed the overall bomb assembly process.
The ranch house and its outbuildings are typical of ranches of the early to mid-20th century in this area of New Mexico. Constructed in stages, the ranch house was built as a one-story adobe structure with a later stone addition, a semi-detached ice house, and a wood porch (since rebuilt). It is surrounded by a low stone wall. The outbuildings are of adobe and stone construction. A Chicago Aeromotor windmill supplied water to two large above-ground concrete reservoirs. Adjacent to the ranch buildings are the remains of several wood and wire-fenced corrals.
