Yellowstone RiverYel·low·stone River
river flowing from NW Wyo. through Mont. into the Missouri River: 671 mi (1,080 km)
Origin of Yellowstone Rivertranslated, translation of French Roche Jaune, uncertain or unknown; perhaps translated, translation of native name
A river, about 1,080 km (670 mi) long, of northwest Wyoming and southern and eastern Montana. It flows northward through Yellowstone Lake and Yellowstone National Park then east and northeast to the Missouri River. The park includes numerous geysers, including Old Faithful.