1957: The AEC distributes “Background Information on Nevada Nuclear Tests” to the press. The booklet describes a small base at Groom Lake called the Watertown Project. The booklet claimed the facility was part of a project to study weather.
1961: The restricted airspace expands upward, but not outward — it measures 5 by 9 nautical miles (9 by 17 kilometers) in size, but extends up to space and is designated R-4808N.
1962: The first A-12 arrives at Groom Lake. The first test flight takes place two months after the aircraft’s arrival to the base. CIA pilots arrive at the base nearly a year later to begin flight training.
1967: The first MiG 21, a Soviet aircraft, arrives at Groom Lake. Officials name the testing program of MiG aircraft “Have Doughnut.” Some pilots begin to call the restricted airspace above Groom Lake “Red Square.”
1977: Years before the public became aware of the Stealth Fighter, the first F-117A prototype arrives at Area 51. It’s called the “Have Blue.”
1982: The first flight of the vehicle known as “Tacit Blue” takes place at Groom Lake. Like the F-117A, Tacit Blue is a stealth vehicle.
1984: The base petitions for an additional 89,000 acres of land to increase the size of restricted space around the facility. Guards forbid the public from entering this area before it is officially withdrawn, raising concern and criticism of illegality from locals and tourists.
1988: A Soviet satellite photographs Area 51. Popular Science magazine runs the photograph, giving most U.S. citizens their first chance to glimpse the secret base.
1989: Robert Frost, a civilian employee at Area 51, dies. An autopsy shows that his body contained high levels of dangerous chemicals like dioxin and dibenzofuran. His widow, Helen, and other affected workers, file a lawsuit against several government officials. Frost claims her husband died as a result of exposure to dangerous chemicals.
1989: Robert Lazar appears on television and claims to have worked on reverse engineering alien technology at a site not far from Groom Lake.
1995: Area 51 acquires two locations popular with tourists and curious locals, Freedom Ridge and White Sides Peak, and closes them to the public. President Clinton signs an executive order exempting Area 51 from legislation and investigation in order to preserve national security.
1996: Nevada names Route 375, formerly known as the “loneliest highway in America,” the “Extraterrestrial Highway.” Skeptics around the world groan in unison.
2007: It appears that crews are building a new hangar, much larger than the existing hangar. One Web site claims the hangar’s size to be 200 by 500 feet (61 by 152 meters) and 100 feet tall (30 meters).
2009: Several former Area 51 staffers, including two former military test pilots, described their work at the site.
2013: Area 51 is identified by that name for the first time in declassified CIA documents, though all operations at the facility are still kept secret. No mention is made of aliens in the documents.