The Pacific Coast was the coast adjacent to the Pacific Ocean, the largest ocean on planet Earth.
In 1893, the San Francisco Register identified itself as the leading newspaper of the Pacific Coast. (TNG: "Time's Arrow")
In 1996, Tuvok described the city of Los Angeles as being on the Pacific coast. (VOY: "Future's End")
In 2153, MacReady recognized San Francisco as being on the Pacific coast. (ENT: "North Star")