From 1947 to 1969, the Air Force investigated Unidentified Flying Objects under Project Blue Book. The project, headquartered at Wright-Patterson Air Force Base, Ohio, was terminated Dec. 17, 1969. Of a total of 12,618 sightings reported to Project Blue Book, 701 remained "unidentified."
The decision to discontinue UFO investigations was based on an evaluation of a report prepared by the University of Colorado entitled, "Scientific Study of Unidentified Flying Objects;" a review of the University of Colorado's report by the National Academy of Sciences; previous UFO studies and Air Force experience investigating UFO reports during the 1940s, '50s and '60s.
As a result of these investigations, studies and experience gained from investigating UFO reports since 1948, the conclusions of Project Blue Book were: (1) no UFO reported, investigated and evaluated by the Air Force was ever an indication of threat to our national security; (2) there was no evidence submitted to or discovered by the Air Force that sightings categor