This report examines the evolving criteria that the Atomic Energy Commission (AEC) used to site nuclear reactors, gaseous diffusion plants, and feed processing, fabrication, and initiator production facilities in the United States. The report begins by exploring how the initial sites of Oak Ridge, Tennessee and Hanford, Washington were chosen. It then gives the history of how later sites were selected. The appendices include a listing of facilities and their critical attributes, such as water and power supply. The report was prepared under government contract for the U.S. Department of Energy (DOE).