Of the 6,700 documents that the FBI has posted publicly at its Vault since 2011, the most popular of them all is ... a 1950 memo on UFOs, reports Live Science. In the so-called Hottel memo, an agent recounts that someone reported seeing three "flying saucers" that crashed in New Mexico, with three apparent dead aliens in each. The agent didn't seem to take it very seriously, concluding that "no further evaluation was attempted."
The memo has been publicly available since the 1970s, but with the launch of the Vault, the one-page memo went viral and has since then received nearly 1 million hits. The FBI again takes pains to point out "the Hottel memo does not prove the existence of UFOs," in its own writeup on the popularity of the document. "It is simply a second- or third-hand claim that we never investigated," possibly the result of a tall tale floating around at the time. "Sorry, no smoking gun on UFOs."