Timeline of U.S. Government UAP Investigations (1947–Present)
A chronological overview of official U.S. government efforts to investigate unidentified flying objects and unidentified anomalous phenomena, from Project Sign in 1948 through Project Blue Book, the Condon Report, the UAP Task Force, and AARO.
The U.S. government has investigated reports of unidentified flying objects (UFOs) — now officially termed unidentified anomalous phenomena (UAP) — for more than seven decades. This timeline outlines the major official programs and milestones, with links to the corresponding records in this archive.
1948–1949: Project Sign and Project Grudge
Following a wave of UFO reports in 1947, the U.S. Air Force established Project Sign in 1948, the first organized U.S. military study of unidentified flying objects. It was reorganized as Project Grudge in 1949. Both produced technical reports now held in the National Archives.
1952–1969: Project Blue Book
In 1952 the Air Force consolidated its UFO work into Project Blue Book, headquartered at Wright-Patterson Air Force Base. Over its life Blue Book reviewed 12,618 reports, of which 701 remained listed as “unidentified.”
1968: The Condon Report
The Air Force funded an independent review by the University of Colorado, published in 1968 as the “Scientific Study of Unidentified Flying Objects” (the Condon Report). It concluded that further study was unlikely to advance scientific knowledge, providing the basis for ending Blue Book.
December 1969: Blue Book closes
The Air Force terminated Project Blue Book on December 17, 1969. No comparable public U.S. government UFO program operated for several decades afterward.
2017–2021: Renewed official attention
In December 2017, news reporting and the release of U.S. Navy videos renewed public attention to the subject. The Department of Defense established a UAP Task Force in August 2020, and in June 2021 the Office of the Director of National Intelligence published a Preliminary Assessment on UAP.
2022–present: AARO and the records collection
In July 2022 the Department of Defense established the All-domain Anomaly Resolution Office (AARO) to investigate UAP across domains; ODNI and the Department of Defense have since published consolidated annual reports. Under the 2024 National Defense Authorization Act, federal agencies began transferring UAP records to the National Archives as Record Group 615, the Unidentified Anomalous Phenomena Records Collection.