Yellowstone National Park was a special preserve with parts in Wyoming, Idaho, and Montana on Earth.
While T'Pol was stationed in Sausalito, she took a five-day leave, visiting Yellowstone National Park as well as Carlsbad Caverns and Carbon Creek, Pennsylvania due to "scientific interest."
Later in 2152, after telling a story about her second-foremother T'Mir, T'Pol listed Yellowstone among the places she visited while on leave on Earth. (ENT: "Carbon Creek")
Scenes for Star Trek: The Motion Picture set on Vulcan were filmed in the park between 8 August and 10 August 1978. [1] [2]