These five postcards date from the late 1910s to the 1960s. The first shows someone feeding a black bear, behavior that the Park Service actively discourages today. The person feeding the bear, though apparently a woman, is wearing pants and a tie, suggesting the group has also been horseback riding.
Click image to download a 348-KB PDF of this postcard.
This postcard has the UP “system” logo and a white border, both of which date it to 1915 to 1930. However, based on the clothing styles, I would guess it is from the early part of that period. The back of the card says Yellowstone is “best reached by the Union Pacific via West Yellowstone Station, directly on the park boundary.” Northern Pacific, whose Gardiner station was directly on the park’s northern boundary, would naturally dispute that claim.