Yellowstone

The name of a major tributary of the Missouri River. The name Yellowstone derives from translations of several indigenous names for the river that refer to the sulfur-containing yellow rocks the river has carried out of the Yellowstone Caldera, an active supervolcano that powers the hydrothermal features of Yellowstone National Park in Wyoming. The Yellowstone River also lends its name to the volcanic hotspot that created the park, a large caldera lake within the park, and the Montana county in which the state's largest city of Billings is located.