
Roswell, New Mexico, 1947: Debris was recovered from a site, in New Mexico, allegedly extraterrestrial, including, some people believed, alien corpses. Officials described the fragments as the remains of a weather balloon. Both the CIA and FBI quickly quashed the rumours, some say too quickly.
Tombaugh's telescope, 1949: Clyde W Tombaugh recorded seeing six or eight rectangular lights in the sky above Las Cruces, New Mexico, and on another occasion several green fireballs. Tombaugh was a leading astronomer whose achievements included the discovery of the dwarf planet Pluto.
Carson Sink, 1952: Two senior U.S. military pilots in a B-25 Mitchell bomber reported they had spotted three aircraft of a type unknown to them. These aircraft were flying at least three times faster than their own plane, the pilots reported. The sighting is still officially classified as unexplained.
Portsmouth, New Hampshire, 1961: Barney and Betty Hill from Portsmouth claimed they had been kidnapped by aliens. The couple said they had been pursued by a flying saucer while travelling in their Chevrolet Bel-Air. It was the first alleged personal encounter with aliens. The couple said they were subjected to a physical examination, and observed a 3-D 'star map' inside the ship.






If that's the best evidence...