The Belle Fourche River (pronounced bel FOOSH; Lakota: Šahíyela Wakpá ) is a tributary of the Cheyenne River, approximately 290 miles (470 km) long, in the U.S. states of Wyoming and South Dakota. It is part of the Mississippi River watershed via the Cheyenne and Missouri rivers. In the latter part of the 19th century, the Belle Fourche River was known as the North Fork of the Cheyenne River.  Belle Fourche is a name derived from French meaning "beautiful fork". 
It rises in northeastern Wyoming, in southern Campbell County, approximately 15 miles (24 km) north of Wright. It flows northeast around the north side of the Bear Lodge Mountains, past Moorcroft and Devils Tower. Near the state line with Montana, it turns abruptly southeast and flows in western South Dakota, past Belle Fourche and around the north side of the Black Hills. In southern Meade County near Hereford, it turns ENE and joins the Cheyenne approximately 50 miles (80 km) ENE of Rapid City.
The point at which the river flows out of Wyoming and into South Dakota is the lowest elevation point in the state of Wyoming at 3,099 feet (945 m). This is the second-highest low point of any U.S. state. 
- Ullrich, Jan, ed. (2011). New Lakota Dictionary (2nd ed.). Bloomington, IN: Lakota Language Consortium. p. 861. ISBN 978-0-9761082-9-0. LCCN 2008922508.
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- Federal Writers' Project (1940). South Dakota place-names, v.3. University of South Dakota. p. 4.
- U.S. Geological Survey. "Elevations and Distances". Archived from the original on 16 January 2008. Retrieved 2008-01-22.
- U.S. Geological Survey Geographic Names Information System: Belle Fourche River
- "The National Map Viewer". U.S. Geological Survey. Retrieved 2012-09-20.