10 In-Universe Star Trek Holidays (And When To Celebrate Them)

Humanity began exploring other solar systems shortly after Zefram Cochrane's first warp flight in 2063, but, with the launch of the Captain Archer's Enterprise in April 2151, humanity began venturing beyond their local neighbouring stars. The Enterprise's warp 5 engine drastically cut down travel times and allowed Humans to make contact with countless new alien societies. Because of its historical importance, the anniversary of the Enterprise's maiden voyage is celebrated every year with a massive parade through space. It was never stated on screen what specific day in April the NX-01 was launched, but Terry Matalas said in a tweet that the holiday was celebrated on the 13th.

In 2401, a Borg/Changeling alliance infiltrated Starfleet and gathered the entire fleet to Earth for the 250th Frontier Day celebration. The Borg then linked the Starfleet ships to an automated network and assimilated everyone under 25 using the ships transporter systems. The Borg Queen was eventually defeated, and the assimilated freed, but a lot of lives were lost in the conflict. So far, this is the only Frontier Day celebration we've seen, but also likely the most eventful.

It's worth noting that Frontier Day also directly follows the anniversary of humanity's first encounter with the Klingon Empire in Broken Bow, making it a kind of lesser known First Contact Day.