(NewsNation) — As Americans prepare for Independence Day celebrations, UFO enthusiasts are marking a different occasion: World UFO Day.

The holiday, observed on July 2, commemorates the anniversary of the 1947 Roswell incident when an Army weather balloon, according to the military, crashed in New Mexico. Some believe it was an alien spacecraft, sparking decades of conspiracy theories about a government cover-up.

Roswell, the self-proclaimed UFO capital of the world, hosts its annual UFO Festival this weekend. City Councilor Juliana Halvorson said Tuesday on NewsNation’s “Elizabeth Vargas Reports” that the event nearly doubles the town’s population.

“Merchants are so successful,” Halvorson said. “We get people from all over the world that come visit us.”

The festival features costume contests, speakers, panels and family-friendly activities. Halvorson emphasized that both believers and skeptics are welcome.

“You get people that are true believers … or you get people that just want to have a bunch of family fun,” she said.

Halvorson noted increased interest in UFO tourism following recent claims by whistleblower David Grusch about alleged government programs involving nonhuman technology and “biologics.” The U.S. government has denied these claims.

While Roswell doesn’t see many UFO sightings nowadays, Halvorson encourages visitors to keep an open mind and explore the town’s UFO museum, which houses the world’s largest UFO library.

“It may change your mind. It may not, but you can at least learn more about what’s going on in the world,” Halvorson said.