Project Blue Book was the United States Air Force's systematic study of UFO reports between 1952 and 1969. It catalogued 12,618 sightings, of which 701 remained classified as 'Unidentified' when the project closed. The full archive is held at the National Archives and is searchable through the Black Vault mirror.
Project Blue Book succeeded the smaller 1947–1948 Project Sign and the 1948–1952 Project Grudge as the Air Force's primary UFO investigative effort. It was based at Wright-Patterson Air Force Base in Dayton, Ohio under the Air Technical Intelligence Center.
Blue Book was directed at various points by Captain Edward J. Ruppelt (who coined the term 'unidentified flying object'), Major Hector Quintanilla, and others. Its scientific consultant for most of its run was astronomer Dr. J. Allen Hynek, whose dissatisfaction with the project's analytical standards led him to found the Center for UFO Studies (CUFOS) after Blue Book closed.
The project was terminated on December 17, 1969 following the conclusion of the 'Condon Report' — the University of Colorado UFO Project commissioned by the Air Force and chaired by physicist Dr. Edward Condon — which recommended further USAF UFO study was not justified. The decision remains contested in the historical literature, and Blue Book's 701 'Unidentified' cases are the foundational dataset for everything downstream.
Where to read the files. The complete declassified Blue Book record is at the National Archives (Record Group 341); the Black Vault hosts a searchable mirror with full-text PDFs of every case file. Both URLs appear on the events linked from this page.
11 entries · sorted newest first
U.S. Air Force security personnel stationed at the twin Royal Air Force bases of Bentwaters and Woodbridge report a triangular, metallic craft on the ground in adjacent Rendlesham Forest, followed by aerial light phenomena two nights later. The deputy base commander signs a memorandum to the U.K. Ministry of Defence summarizing the events.
More than two hundred students and staff at Westall High School in suburban Melbourne report observing a low, disc-shaped object descend behind a stand of pine trees, then ascend rapidly. The case is widely cited as Australia's most-witnessed UAP event.
A New Hampshire teenager and two Exeter, New Hampshire, police officers report a large, silent, brightly lit object hovering at low altitude over a residential field. The Air Force initially attributes the sighting to a high-altitude refueling mission, then revises the case to 'unidentified.'
Eleven members of an extended family in rural Kentucky report being besieged through the night by small, silver-coated humanoid figures. The Hopkinsville Police, Kentucky State Police, and U.S. Air Force investigate.
Three-volume Air Force Office of Special Investigations dossier (Box 7) containing 233 incident summary reports from 1955. Released by the Department of War as part of PURSUE Release 01.
Across two consecutive weekends, multiple radar installations and visual observers track unidentified objects above the restricted airspace surrounding the U.S. Capitol and White House. The Air Force convenes its largest press conference since World War II to address the events.
Air Force Office of Special Investigations file box 186, folder 319.1 'Flying Discs' — 143 pages of 1949-era investigative material. One of the earliest organized USAF UAP file holdings.
Kentucky Air National Guard pilot Capt. Thomas Mantell is killed when his P-51 Mustang crashes during the pursuit of a large, slow-moving object reported above Godman Field. The Air Force eventually attributes the object to a Skyhook research balloon.
The Roswell Army Air Field public information officer issues a press release stating that the 509th Bomb Group has come into possession of a 'flying disc' recovered from a nearby ranch. Within twenty-four hours the Army retracts the statement and identifies the debris as a weather balloon.
Civilian pilot Kenneth Arnold reports nine crescent-shaped objects flying in formation near Mount Rainier at speeds he estimates at more than 1,200 mph. His description gives rise to the term 'flying saucer' and is widely treated as the start of the modern UFO era.
Air Materiel Command and Army Air Forces general files covering 1946–1948 UFO investigations conducted before Project Blue Book's formal establishment. Includes the Maury Island and Roswell-era investigative correspondence.
Non-fiction titles by named witnesses, Pentagon insiders, and investigative journalists referenced in this archive.
Affiliate disclosure: as an Amazon Associate, Disclosure Archives earns from qualifying purchases.
U.S. material is the single largest body in the public UAP record, but it isn't the only one. France's GEIPAN has run a transparent case database since 1977; the UK MoD released ~60,000 pages between 2008 and 2017; Japan's evolving track is the program currently moving fastest in 2026. Every state-run UAP-investigation body with a public archive — fifteen countries to date — is catalogued in one place.
Browse international government archives →Looking for related material? Browse the full timeline, the on-the-record witnesses, or every topical tag.