Following the United States entry into the second world war, the Manhattan Project emerged as a massive coordinated program to pursue development of nuclear weapons. Leading scientists such as Robert Oppenheimer, Glenn T. Seaborg, Enrico Fermi and Edward Teller were among the thousands of civilian scientists and engineers employed in the unprecedented wartime efforts. Entire communities were created to support the scientific and industrial aspects of the nuclear efforts in Los Alamos, New Mexico; Oak Ridge, Tennessee; the Hanford site in Washington and elsewhere.