The Manhattan Project was an unprecedented, top-secret World War II government program in which the United States rushed to develop and deploy the world’s first atomic weapons before Nazi Germany. The use of these weapons by the United States against Japan in August 1945 ultimately became one of the most important historical events of the 20th century. The project ushered in the nuclear age and left enduring legacies that echo all around us today. The Manhattan Project took shape at three primary locations across the country: Hanford, Washington; Los Alamos, New Mexico; and Oak Ridge, Tennessee.