Between 1947 and 1969, 12,618 sightings were reported to Project Blue Book, a project into UFO research that was headquartered at Wright-Patterson Air Force Base. To this day, 701 of the sightings remain "Unidentified."
One of the first and most famous involved businessman and pilot Kenneth Arnold, who was flying near Mt. Rainer, Wash. on June 24, 1947, when he reportedly sighted nine unidentified flying objects. The press later used his various descriptions to come up with the term flying saucer.