1947-1969
The Air Force's best-known public UFO investigation accumulated thousands of reports, closed most of them, and left a smaller set classified as unidentified.
Claim ledger
Status belongs to a specific claim, not to a person, institution, or side.
The National Archives holds the declassified administrative and case records. The Air Force ended the program in 1969.
Archived case files, administrative records, photographs, and an Air Force fact sheet.
No contrary evidence recorded in this entry.
The Air Force fact sheet counted 12,618 reports and left 701 categorized as unidentified.
No affirmative evidence recorded in this entry.
The Air Force's own published count includes 701 unidentified cases.
Unidentified means the available investigation did not settle a case. It does not, by itself, identify an extraterrestrial cause.
Some reports remained unexplained after the available investigation.
The archive does not establish a single common cause for the unresolved cases.
Project Sign begins the Air Force's postwar investigation of reported flying objects.
Project Blue Book begins under that name.
The Air Force terminates Project Blue Book.
U.S. National Archives. Archive holdings, Air Force fact sheet, Roswell summary, and MJ-12 reference findings.
U.S. National Archives. Historical context and examples from the archived case files.