Despite attracting the attention of millions around the world, only a tiny fraction of people made it to the gates of the secret Area 51 military base for the scheduled September 20 raid.
About 1500 curious Earthlings from around the globe travelled to festivals in the towns in the Nevada desert surrounding the base on Friday (local time).
They were drawn by an internet buzz and a social media craze sparked by a summertime Facebook post inviting people to "Storm Area 51".
"They can't stop all of us," the post joked.
"Let’s see them aliens."
In the end — at the appointed hour of 3am on September 20 — only about 75 to 100 people braved chilly darkness and a bumpy, dusty 13-kilometre drive to the Rachel gate of the legendary former top-secret US Air Force base.
Another 40 travelled about 32 kilometres down a more rugged washboard-dirt road to a different gate.
The sheriff in neighbouring Nye County reported about 40 people gathered overnight at a conspicuously green "Area 51 Alien Centre" in Amargosa Valley about 3am and approached a base gate before leaving after "heated warnings" from officers.
No one found UFOs or space aliens, Lincoln County Sheriff Kerry Lee said.
They did find they weren't alone, amid bright floodlights, watchful cameras and who-knows-what in a squat tan bunker building with blackout windows — all surrounded by razor wire.
Polite and patient local sheriff's deputies ushered one woman away when she stepped too far forward.
They arrested a man from Canada who urinated near the gate and cited him for indecent exposure, Lee said. The woman was released with a warning.
"We intend to keep those officers there throughout the event," Sheriff Lee told reporters on Friday.
"You know: Come. Look. See what you can see. But just don't cross."
As he spoke, a trickle of vehicles grew to a stream on a two-lane state road dubbed the Extraterrestrial Highway toward Rachel, a town of 50 residents now hosting more than 2000 "Alienstock" campers and alien-seekers.
Another event started in Hiko, a crossroads town a 45-minute drive closer to Las Vegas.
Meanwhile, Matty Roberts, a 20-year-old from Bakersfield in California, who sparked the Area 51 phenomenon with a late-night Facebook post and then broke with Little A'Le'Inn owner Connie West over production of the Rachel event, hosted a Thursday evening event at an outdoor venue in downtown Las Vegas also using the "Alienstock" name.
"It started as a joke and now people are getting to know each other," Tracy Ferguson – a 23-year-old from Sioux Falls, South Dakota, who said the internet gave him the idea to drive to Nevada with his 19-year-old girlfriend, Jade Gore, of Worthington, Minnesota – said.
Ms Gore quit her job at a Dairy Queen and dyed her hair and eyebrows green.
They drove through Wyoming, Utah and into Nevada with "Area 51 bound" and "Comin 4 Dem Alien Cheeks" in green paint on their car windows.
"People were taking pictures and laughing the whole way," Ms Gore said.
By noon they'd visited the Little A'Le'Inn in Rachel, the Alien Research Centre in Hiko and the Rachel gate to Area 51.
"Area 51 Basecamp" in Hiko was set to feature music, speakers and movies — headlined by an electronic dance music DJ who tours the world and attracts packed clubs on the Las Vegas Strip.
Alien Research Centre owner George Harris said he expected a crowd of 5000.
Michael Ian Borer, a University of Nevada, Las Vegas, sociologist who researches pop culture and paranormal activity, called the festivities a blend of interest in aliens, the supernatural, government conspiracies and the desire to know what is unknown.
A sheriff's deputy at the Rachel gate ticked off the countries he said visitors came from – Russia, Germany, Peru and Sweden.
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