Middle Mississippi River

The Mississippi River is known as the Middle Mississippi from the Upper Mississippi River's confluence with the Missouri River at St. Louis, Missouri, for 190 miles (310 km) to its confluence with the Ohio River at Cairo, Illinois.

The Middle Mississippi is a relatively free-flowing river. From St. Louis to the Ohio River confluence, the Middle Mississippi falls a total of 220 feet (67 m) over a distance of 180 miles (290 km) for an average rate of 1.2 feet per mile (23 cm/km). At its confluence with the Ohio River, the Middle Mississippi is 315 feet (96 m) above sea level. Apart from the Missouri River, no major tributaries enter the Middle Mississippi River.

Measured by length, the Middle Mississippi's primary branch is the Missouri River, not the Upper Mississippi, whether or not additional tributaries upstream are considered. Thus, by length, the main branch of the Mississippi River system at St. Louis can be considered to be the Missouri River, rather than the Upper Mississippi. By taking the longer branch at each significant fork, this continuous but multiply named waterway can be identified and measured. One name for it is the Lower & Middle Mississippi-Missouri-Jefferson-Beaverhead-Red Rock-Hellroaring Creek River. The name "Great American River" has also been suggested for this longest American waterway.

Posted in: Names and Tributaries