First Contact Day — memory alpha

Multiple realities

(covers information from several alternate timelines)

First Contact Day was a holiday celebrated to honor both the warp 1 flight of the Phoenix and first open contact between Humans and Vulcans on April 5^th, 2063 in Bozeman, Montana. (Star Trek: First Contact)

The mirror universe equivalent of First Contact Day was also on April 5^th. Instead of peacefully greeting the Vulcans, the Terrans slaughtered all of the members of the survey ship. The day was later celebrated as a holy day, though not a high holy day, by the Terran Empire. (ENT: "In A Mirror, Darkly"; DIS: "Die Trying")

When Captain Kathryn Janeway was a child, the holiday was just considered a day off from school. (VOY: "Homestead") WSA continued to operate on First Contact Day, however. (ST: "Children of Mars")

Naomi Wildman and Neelix planned the 315th observation of the event aboard the USS Voyager. The festivities included Zefram Cochrane's favorite food, cheese pierogies, and rock and roll music on Tom Paris' jukebox. At Neelix's insistence, Tuvok gave the Vulcan salute while reciting the greeting given by the Vulcans during first contact: "Live long and prosper." He did not see the point of it, but everyone in attendance applauded. (VOY: "Homestead")

During a battle in 2380, Commander Jack Ransom noted the USS Cerritos was being "carved up like a First Contact Day salmon." (LD: "No Small Parts")

On this day in 2385, the planet Mars was attacked by rogue synths. 92,143 people died in the attack. (ST: "Children of Mars"; PIC: "Remembrance", "Maps and Legends")

Kovich was born on First Contact Day of an unknown year. (DIS: "Die Trying")

Appendices

Star Trek: First Contact co-writer Ronald D. Moore chose the date for first contact in honor of his son, Jonathan, whose birthday is April 5^th. (Star Trek Encyclopedia, 4th ed., vol. 1, p. 273; (AOL chat, 1997))
First Contact Day was also cited in the first draft of the script for ENT: "Fusion" (which had the working title "Equilibrium"). In that script, Trip Tucker told Fraht about this holiday, commenting about it, "'That's kind of dull... just an excuse for kids to get the day off from school."
First Contact Day has become adopted by the Star Trek franchise in the real world as a date to publicly celebrate Star Trek in the broadest sense as an elaborate annual public relations event, and uses the occasion to announce new releases for that year – those of merchandise in particular. The event was instituted in 2021, in the midst of the COVID-19 pandemic lockdowns as a kind of a "pick-me-up" (the first event therefore conducted virtually by remote digital means), ànd to celebrate the 25th anniversary of First Contact, the film in which the date was established. [1]