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What is Project Blue Book?
Project Blue Book was the U.S. Air Force's main program for investigating UFO reports. It was based at Wright-Patterson Air Force Base in Ohio and ran from March 1952 until the Air Force Secretary announced its end on December 17, 1969. Counting its predecessor projects back to 1947, the Air Force logged 12,618 sightings, and 701 of them remained 'unidentified'. The Air Force concluded none showed a threat to national security or evidence of extraterrestrial vehicles.
Key dates
- 1948-01 — Project Sign, the Air Force's first formal UFO study and a predecessor of Blue Book, began; it was renamed Project Grudge around February 1949. All-domain Anomaly Resolution Office, U.S. Department of Defense
- 1952-03 — Air Force intelligence chief Maj. Gen. Charles Cabell set up Project Blue Book at Wright-Patterson AFB, with Capt. Edward J. Ruppelt as its first leader. All-domain Anomaly Resolution Office, U.S. Department of Defense
- 1969-12-17 — Air Force Secretary Robert Seamans Jr. announced that Project Blue Book was ending. U.S. National Archives and Records Administration
- 2024-03-08 — The Pentagon's AARO published a historical review that drew on Blue Book's 7,252 files at the National Archives and repeated its finding that 701 of 12,618 sightings were unidentified. All-domain Anomaly Resolution Office, U.S. Department of Defense
Last reviewed 2026-10-18. Statements are attributed to the linked sources; inclusion on this page does not imply wrongdoing.
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Blue Book was an early government UAP investigation program, preceding AATIP by decades. The gap between Blue Book's closure (1969) and AATIP's creation (2007) remains a period of disputed government UAP activity.
Frequently asked questions
Why was Project Blue Book shut down?+
According to the National Archives, the Air Force based its decision on the University of Colorado study, a National Academy of Sciences review of that study, earlier UFO studies and its own experience investigating reports. It concluded that no UFO had shown any threat to national security, technology beyond then-current science, or evidence of extraterrestrial vehicles. U.S. National Archives and Records Administration
How many UFO sightings did Project Blue Book investigate?+
The National Archives says 12,618 sightings were reported to Project Blue Book from 1947 to 1969, a count that includes its predecessor projects. Of those, 701 remained unidentified. U.S. National Archives and Records Administration
Where are the Project Blue Book files?+
The Air Force transferred the records to the National Archives. They have been declassified and are available on 94 rolls of microfilm (publication T-1206), with the names of witnesses withheld from public access. U.S. National Archives and Records Administration
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