Newly declassified documents provide an official U.S. government history of Area 51

The United States National Security Archive has released 355 pages of previously classified information on Area 51.

For decades, the remote region of the southern Nevada desert has been the subject of countless conspiracy theories. Most speculation about the secret government site relates to theories about an alien crash concealed by the U.S. government.

The document released today (August 15) by the National Security Archive claim that in its early days, Area 51 was primarily used by the Central Intelligence Agency as a testing ground for the first U-2 recognisance aircraft, a classification of spy plane that is still used by the U.S. military. That program was known "Project Aquatone".

The U-2 is notable for the extremely high altitudes at which it can fly.

“Many important areas of the Soviet Union lay beyond the range of existing reconnaissance aircraft,” one page of the document reads. “The Air Force had therefore begun to develop a high-altitude reconnaissance aircraft that would be able to conduct deep-penetration reconnaissance missions over the Soviet Union.”

It continues: “The Agency's manned overhead reconnaissance program lasted 20 years. It began with President Eisenhower's authorization of the U-2 project in late 1954 and ended with the transfer of the remaining Agency U-2s to the Air Force in 1974.”

A blog post a Foreign Policy quoting a history of the CIA notes that alleged UFO sightings in southern Nevada began to be reported almost immiedatly after testing of the U-2 aircraft began.

"The U-2's operating altitude of 60,000 feet was higher than any other aircraft at the time -- higher than some people even thought possible," it reards. "If a U-2 was airborne in the vicinity of the airliner [during twilight hours]...its silver wings would catch and reflect the rays of the sun and appear to the airliner pilot, 40,000 feet below, to be fiery objects."

The National Security Archive document is titled “The Central Intellifence Agency and Overhead Reconnaisance: The U-2 and the OXCART Programs, 1954 – 1974”. You can view it in its entirety here (warning: large PDF download).