Area 51 'declassified' in U-2 spy plane history
16 August 2013

The CIA has officially acknowledged the secret US test site known as Area 51, in a newly unclassified internal history of the U-2 spy plane programme. The document obtained by a US university describes the 1955 acquisition of the Nevada site for testing of the secret spy plane....

The remote patch of desert surrounding Groom Lake was chosen because it was adjacent to a nuclear testing facility.  "The U-2 was absolutely top secret," Chris Pocock, a British defence journalist and author of histories of the programme, told the BBC.
"They had to hide everything about it."

The U-2 plane, developed to spy on the Soviet Union during the Cold War, is still flown by the US Air Force.  The document, a secret 1992 internal CIA history of the U-2 programme, was originally declassified in 1998 with heavy redactions.

Many of the blacked-out details were revealed this month after a public records request by the National Security Archive at the George Washington University in Washington DC. The site was selected for the U-2 programme in 1955 after an aerial survey by CIA and Air Force staff.

According to the history, President Dwight Eisenhower personally signed off on the acquisition.
Officials from the CIA, Air Force and Lockheed, the contractor building the U-2, began moving into the facility in July 1955....
http://www.bbc.co.uk/news/world-us-canada-23731759