GovernmentWright-Patterson AFB, OH

Project Blue Book begins

First page of a typed 1966 U.S. Air Force Project Blue Book summary document
A 1966 Air Force summary of Project Blue Book, the program begun in 1952 US Governement, Public domain, via Wikimedia Commons

The Air Force reorganized its UFO investigations as Project Blue Book. By the time it closed in 1969, the Air Force programs had logged 12,618 reports, 701 of them still listed as unidentified.

Evidence
Significance

Sources

  1. OfficialProject Blue Book 50th AnniversaryU.S. National Archives / 2019-12-05
  2. OfficialUnidentified Flying Objects and Air Force Project Blue Book (fact sheet)U.S. Air Force
  3. OfficialUFOs and UAPs research guide (Project Blue Book records)U.S. National Archives

How sources are chosen and tiered