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 (Nevada) National Wildlife Refuge Complex. In another effort to help protect and preserve the fragile habitats in the Muddy Springs area, the Southern Nevada Water Authority (SNWA) and various environmental associations have organized an effort to conserve these species. The area was part of the Native American Paiute peoples homeland for centuries, with the Mojave to the south. "Moapa" is a Southern Paiute language word meaning "muddy"; although "Moapa River" was formerly the official name, local usage tended to translate the name, and it was made official in 1960. The Old Spanish Trail originally followed the Virgin River all the way