What Is Known (and Not Known) About Area 51

Area 51 Britannica file video — Encyclopedia Britannica Inc.

Area 51 has spawned more conspiracy theories than perhaps any other military facility in the world. Here’s what we know (and don’t know) about this U.S. military installation.

What we know about Area 51:

Area 51 is a U.S. Air Force military installation located at Groom Lake in southern Nevada.
Area 51 is an active military installation. It is administered by Edwards Air Force Base in southern California.
Area 51 is not accessible to the public and is under 24-hour surveillance.
The only confirmed use of the installation is as a flight-testing facility.
The site is known as Area 51 because that was its designation on maps created by the Atomic Energy Commission.
During World War II (1939–45) the U.S. Army Air Corps used the site as an aerial gunnery range.
In 1955 the area was selected by the Central Intelligence Agency (CIA) as a testing site for the Lockheed U-2, a high-altitude reconnaissance aircraft. Pres. Dwight D. Eisenhower (1953–61) authorized the testing, which was to be conducted under the code name Project AQUATONE. Testing began in July 1955.
After the U-2 was put into service in 1956, Area 51 was used to develop other aircraft, including the A-12 (also known as OXCART) reconnaissance plane and the stealth fighter F-117 Nighthawk.
In 1989 a man named Robert (“Bob”) Lazar claimed he worked on extraterrestrial technology inside Area 51. Lazar told Las Vegas television reporter George Knapp that he saw autopsy photographs of aliens inside the facility and that the U.S. government used the facility to examine recovered alien spacecraft. Although Lazar himself was discredited, his claims spawned numerous government conspiracy theories, most of which involved extraterrestrial life.
Many people have reported seeing unidentified flying objects (UFOs) in or near Area 51. (Although the term is often used in the context of extraterrestrial speculation, UFOs are not necessarily extraterrestrial in origin.)
On June 25, 2013, the CIA approved for release declassified documents chronicling the history of the U-2 and OXCART programs. The documents were released in response to a Freedom of Information Act (FOIA) request submitted in 2005 by American intelligence historian Jeffrey T. Richelson of the George Washington University National Security Archive. The release of the documents marked the first time that the U.S. government formally acknowledged the existence of Area 51.
According to the CIA, test flights of the U-2 and subsequent military aircraft account for the UFO sightings in the area.
Area 51 employees reach the facility by way of airplane. They fly in and out of a restricted terminal at McCarran International Airport on one of several unmarked planes permitted to fly through the airspace above Area 51 (airspace R-4808N).
Until recently, satellite imagery of the installation was censored. Area 51 is visible on Google Maps.

What we don’t know about Area 51:

The U.S. government has not provided any information about the research currently being conducted inside the facility.