Yellowstone National Park

Yellowstone National Park

West Thumb of Yellowstone Lake

Members of the 1870 Washburn party noted that Yellowstone Lake was shaped like "a human hand with the fingers extended and spread apart as much as possible," with the large west bay representing the thumb. In 1878, however, the Hayden Survey used the name "West Arm" for the bay; "West Bay" was also used. Norris' maps of 1880 and 1881 used "West Bay or Thumb." During the 1930s, park personnel attempted to change the name back to "West Arm," but West Thumb remains the accepted name.

Visitor Information
307-344-7381 (recorded information)