|The Department of Energy Grand Junction Office is nationally significant under Criterion A under the Military, Industry, and Politics/Government areas of significance for its role in the Manhattan Project and Cold War from 1943 to 1970. The 1943 initial date for the Period of Significance is when the Materials Section of the Manhattan Engineer District established the site as its headquarters for the procurement of domestic uranium for the Manhattan Project. The 1970 terminal date of the Period of Significance is derived from the date when the federal government ceased purchase of domestic uranium for Cold War weapons production. The office complex retains rare resources from the 1943-1945 Manhattan Project, which developed the world's first nuclear bomb. All of the domestically-acquired uranium used by the Manhattan Project (14.2% of the total uranium) was obtained by personnel working at the office, concentrated on site, and shipped to other Manhattan Project facilities in Tonawanda, New York; Oak Ridge, Tennessee; Hanford, Washington; and Los Alamos, New Mexico for further refinement, enrichment, and incorporation into test devices and the bombs detonated over Hiroshima and Nagasaki to end World War II.