Ohio River course forms the northern borders of West Virginia and Kentucky; and the southern borders of Ohio, Indiana and Illinois, until it joins the Mississippi River at the city of Cairo, Illinois. Where the Ohio joins the Mississippi is the lowest elevation in the state of Illinois, at . The Ohio River, which flows westward from Pittsburgh, Pennsylvania, to Cairo, Illinois, is the largest tributary, by volume, of the Mississippi River in the United States. At the confluence, the Ohio is considerably bigger than the Mississippi. Measured by long-term mean discharge in cubic feet per second and cubic meters per second,
Muddy River (Washington) Muddy River (Washington) The Muddy River is a stream, about long, southeast of Mount St. Helens in the U.S. state of Washington. The Muddy River flows south–southeast and joins the Lewis River just above the Swift Reservoir. The Lewis River flows west and is a tributary to the Columbia River. The east flank of Mount St. Helens is within the watershed of Muddy Creek. During the 1980 eruption of Mount St. Helens, lahars (volcanically-induced mud and debris flows) swept through its channel. About of stream channels around the volcano were affected by lahars. The United States Forest Service maintains the