State Route 375 is an actual state highway in Nevada, but because of its proximity to Area 51, it's been officially designated by Nevada as the Extraterrestrial Highway. The strip is 98 miles long, connecting State Route 318 to U.S. Route 6, and running through what is basically empty desert. The area became a tourist destination because it's close to Area 51, the highly secret military base about which there are innumerable stories about aliens and UFOs, so in 1996 the state renamed the highway.
To learn more about the area's history, head for the tiny town of Rachel, roughly in the middle of the 98-mile stretch of highway, where everything is about aliens. There are Area 51 tours that include the Extraterrestrial Highway and Rachel.