The national frame: 1947 and the Air Force investigations

Item 1 — Sign, Grudge and Blue Book, stated once from the National Archives' published record

Every case in this section sits inside one federal paper trail, and the National Archives' own account of it is short enough to state whole. The modern era opens on 24 June 1947, when private pilot Kenneth Arnold, searching over Mount Rainier, Washington, reported nine objects flying at approximately 1,700 miles per hour and described them as "appearing like saucers skipping on water" — shortened by the press to "flying saucers." The flood of reports that followed moved the Air Force Chief of Staff, on 30 December 1947, to order a project "to collect, collate, evaluate, and distribute within the government all information concerning sightings which could be construed as of concern to national security." That project was Sign: headquartered, like its successors, at Wright-Patterson Air Force Base in Dayton, Ohio; it evaluated 243 reported sightings and closed in February 1949 with the verdict that there was "no definite and conclusive evidence … that would prove or disprove the existence of these unidentified objects as real aircraft of unknown and unconventional configuration." Grudge, its scaled-down continuation, evaluated 244 reports and concluded in August 1949 that the reports were misinterpretations of natural phenomena, man-made aircraft, fabrications, or hoaxes. Blue Book, ordered by Air Force Director of Intelligence Maj. Gen. Charles P. Cabell in March 1952, ran until Secretary of the Air Force Robert C. Seamans, Jr. terminated it on 17 December 1969, operations ending in January 1970. Across the three projects the Air Force scientifically analyzed 12,618 reports in the Archives' count. The Air Force transferred its UFO investigation records to the National Archives in 1975; after an interagency redaction of personally identifiable information, the collection opened to public research in the spring of 1976. Each case file, in the Archives' description, relates to one sighting or a group of closely related sightings and holds observer reports, correspondence, newspaper and magazine clippings, and analyses of photographs and physical evidence, with a control sheet summarizing the sighting and the Air Force's explanation and conclusions.

Sources:

1. National Archives News, "Public Interest in UFOs Persists 50 Years After Project Blue Book Termination," 5 December 2019 — Arnold sighting; the 30 December 1947 order; Sign (243 reports, December 1947–February 1949); Grudge (244 reports, ended August 1949); Blue Book (March 1952–17 December 1969); 12,618 reports in total; records transferred 1975, opened 1976; case-file contents described.