The Air Force's own summary: Blue Book ran from Wright-Patterson AFB, was terminated on 17 December 1969, logged 12,618 sightings with 701 unidentified, and closed on the basis of the Colorado report and its NAS review.
“Of a total of 12,618 sightings reported to Project Blue Book, 701 remained “unidentified.”” source
af.mil blocks some automated readers (HTTP 403); the page was read in full through a scraping service. The fact sheet carries no publication date. Archived copy: http://web.archive.org/web/20240922041032/https://www.af.mil/About-Us/Fact-Sheets/Display/Article/104590/
OFFICIALUS National Archives and Records Administration · DATE TO VERIFY
NARA's research page for the Blue Book records: the same totals (12,618 sightings, 701 unidentified), the 17 December 1969 termination, and access to the case files on 94 rolls of microfilm (T1206).
“The project closed in 1969 and we have no information on sightings after that date.” source
OFFICIALUS National Archives and Records Administration (Guide to Federal Records) · DATE TO VERIFY
The administrative history: Project Sign set up by a 30 December 1947 memo, renamed Grudge in February 1949, reactivated in October 1951 and renamed Blue Book in March 1952. Lists case files, 20 film reels, 23 sound recordings and 8,360 photographs.
OFFICIALUS National Archives and Records Administration (National Archives Catalog) · 1969
The case-file series itself, 1947–1969, in Record Group 341, microfilm publication T1206. Each file holds the witness report and a control sheet with the Air Force's explanation; observers' names were removed for privacy.
The catalog page loads its content by script; the series description was read through the catalog's own data service for the same identifier.
OFFICIALAll-domain Anomaly Resolution Office, US Department of Defense · 2024-03-08
AARO's review of US investigations since 1945. Covers Sign, Grudge and Blue Book: dates, leaders, Hynek as lead scientific investigator, Blue Book's three-way case categories, its conclusions, and AARO's own pass through the archived files.
“There was no evidence indicating that sightings categorized as unidentified are “extraterrestrial vehicles.”” source
Report dated February 2024, cleared for publication 6 March 2024 and released 8 March 2024.
OFFICIALDr. Edward U. Condon, University of Colorado (under US Air Force contract) · 1968
The Colorado study's conclusions. It saw no defence problem in UFO reports and thought the defence function could be done without a special unit such as Blue Book, while calling that a question for defence specialists.
“It is our impression that the defense function could be performed within the framework established for intelligence and surveillance operations without the continuance of a special unit such as Project Blue Book, but this is a question for defense specialists rather than research scientists.” source
Electronic edition by the National Capital Area Skeptics, made with permission of the Regents of the University of Colorado.
OFFICIALUS Department of Defense, Office of Public Affairs (DoD FOIA reading room) · 1969-12-17
Primary press release of 17 December 1969 announcing the termination of Project Blue Book, citing Secretary Seamans' memo to Gen. John D. Ryan; notes that the Colorado report was released to the public in January 1969 and that records go to the USAF Archives at Maxwell AFB.
“cannot be justified either on the ground of national security or in the interest of science” source
Opened 2026-10-31 (Argus batch 1).
CLASSIFIEDDeclassifiedFILE NO. 012SHEET 2 OF 3
Testimony
Interviews and witness statements: who, in what role, when and where it was said.
WITNESSDr. J. Allen Hynek, Northwestern University; scientific consultant to the US Air Force on UFOs · 1968-07-29
Hynek's prepared statement and the questions that followed. He describes being asked in 1948 to sort out reports with an astronomical cause, and criticises the lack of serious follow-up of reports.
“it is not their mission to be scientifically curious about the hundreds of unidentified cases in their own files” source
Web transcription by the National Capital Area Skeptics. The official printed hearing (CHRG-90hhrg97818) is on govinfo: https://www.govinfo.gov/app/details/CHRG-90hhrg97818/CHRG-90hhrg97818
CLASSIFIEDDeclassifiedFILE NO. 012SHEET 3 OF 3
Analysis
Our own reading of the file, written from the sources on the other sheets. Opinion is marked as such.
The core of this file is not in dispute. The Air Force ran an official UFO investigation for over two decades, kept count, and published its totals: 12,618 reports, 701 unidentified. Three official sources give the same figures, and the case files themselves are open to anyone at the National Archives, with the names of witnesses removed.
What Blue Book concluded is narrower than it is often remembered. It said no report showed a threat to national security, no evidence of technology beyond the science of the day, and no evidence that the unidentified cases were extraterrestrial vehicles. It did not explain the 701. Those cases were closed as unidentified, not solved.
The quarrel has always been about method, not numbers. The project's own scientific consultant, J. Allen Hynek, told Congress in 1968 that the unidentified cases were never followed up properly. Its first chief, Edward Ruppelt, later wrote that he was expected to explain away every report (as summarised in AARO's 2024 review). AARO's 2024 review found no evidence of a policy to hide extraterrestrial material. Both points can be true at once.
What it shows
That the US Air Force formally investigated UFO reports from 1947 to 1969 and logged 12,618 of them.
That 701 cases stayed unidentified when the project closed, by the Air Force's own count.
That the Air Force concluded there was no threat and no evidence of extraterrestrial vehicles, and closed the project on 17 December 1969.
What it doesn't prove
That the 701 unidentified cases were anything extraordinary. “Unidentified” means the project could not name a cause, often for lack of data.
That every identified case was correctly identified. Critics, including the project's own consultant, said the follow-up was thin.
That the Air Force stopped receiving reports after 1969. The National Archives simply holds no Blue Book records after the closure.
The other side
The totals are official, but critics say they flatter the work behind them. J. Allen Hynek, the Air Force's scientific consultant on UFOs since 1948, told Congress in 1968 that there had been little serious follow-up of reports, and that the Air Force did not see it as its mission to be scientifically curious about the unidentified cases in its own files. On this reading, Blue Book was a sorting office, not a study, and its conclusions say more about its remit than about the phenomena.
Majestic Archive
