This is from the USAF (US Air Force) website, www.af.mil, it is called a 'fact sheet'.

Unidentified Flying Objects and Air Force Project Blue Book

From 1947 to 1969, the Air Force investigated Unidentified Flying Objects under Project Blue Book. The project, headquartered at Wright-Patterson Air Force Base, Ohio, was terminated Dec. 17, 1969. Of a total of 12,618 sightings reported to Project Blue Book, 701 remained "unidentified."

The decision to discontinue UFO investigations was based on an evaluation of a report prepared by the University of Colorado entitled, "Scientific Study of Unidentified Flying Objects;" a review of the University of Colorado's report by the National Academy of Sciences; previous UFO studies and Air Force experience investigating UFO reports during 1940 to 1969.

As a result of these investigations, studies and experience gained from investigating UFO reports since 1948, the conclusions of Project Blue Book were:

• No UFO reported, investigated and evaluated by the Air Force was ever an indication of threat to our national security;
• There was no evidence submitted to or discovered by the Air Force that sightings categorized as "unidentified" represented technological developments or principles beyond the range of modern scientific knowledge; and
• There was no evidence indicating that sightings categorized as "unidentified" were extraterrestrial vehicles.

With the termination of Project Blue Book, the Air Force regulation establishing and controlling the program for investigating and analyzing UFOs was rescinded. Documentation regarding the former Blue Book investigation was permanently transferred to the Modern Military Branch, National Archives and Records Service, and is available for public review and analysis.

Since the termination of Project Blue Book, nothing has occurred that would support a resumption of UFO investigations by the Air Force. Given the current environment of steadily decreasing defense budgets, it is unlikely the Air Force would become involved in such a costly project in the foreseeable future.

There are a number of universities and professional scientific organizations that have considered UFO phenomena during periodic meetings and seminars. A list of private organizations interested in aerial phenomena may be found in "Encyclopedia of Associations," published by Gale Research. Interest in and timely review of UFO reports by private groups ensures that sound evidence is not overlooked by the scientific community. Persons wishing to report UFO sightings should be advised to contact local law enforcement agencies.

Point of Contact:
Requests for copies of records and general information about Project Blue Book should be sent to: Modern Military Records, National Archives, 8601 Adelphi Rd, College Park, MD 20740-6001, (301)713-7250