This image shows Graves Lake and the Wind River Mountains in the background. The Wind River is an upstream source for the Bighorn River.
The description states simply:
#3999 Graves Lake and rugged Wind River Mountains in the Wind River Wilderness area of Wyoming.
–The continental divide follows the crest of the Wind River Mountains, meaning that water on the eastern side of the mountains flows to the Gulf of Mexico, and to the west into the Pacific Ocean.
This card was used and is dated 1 Sept 1956.