Star Trek: First Contact (1996)

On April 4, 2063, aerospace engineer Zefram Cochrane launches the Phoenix from a converted nuclear missile silo in Bozeman, Montana — the first human-built warp-capable ship. The flight lasts only a few minutes and reaches a speed of warp 1. Cochrane lands and celebrates with a bottle of tequila. He has no idea that a Vulcan survey ship has detected his warp signature and is already altering course, or that a starship from the 24th century is watching from orbit to make sure history goes the way it's supposed to.

On April 5, 2063, a Vulcan survey ship lands in a field near Bozeman, Montana, drawn by the warp signature of Zefram Cochrane's Phoenix from the previous day. Cochrane walks out to meet them. It is humanity's first confirmed contact with an alien civilisation, and the moment Earth begins its path toward the United Federation of Planets. First Contact Day is subsequently observed across the Federation every April 5th.