Missouri-Mississippi River

The Missouri-Mississippi River system at about 3,900 miles (6,300 km) in length, it is the fourth longest river in the world. Its average discharge of water makes it the tenth largest river in the world. It is the only river located in North America that made the top ten longest rivers list. Also, its name comes from an Ojibwe word meaning “Great River”. About 98.5 percent of this river is located within the United States, the rest resides in Canada.

For at least 10,000 years, Native Americans have lived along the Mississippi and its tributaries. Most were hunter-gatherers or herders, but some such as the Mound builders formed prolific agricultural societies. The arrival of Europeans in the 1500s forever changed the native way of life as first explorers, then settlers, ventured into the basin in increasing numbers. The river served first as barrier – forming borders for New Spain, New France, and the early United States – then as vital transportation artery and communications link. In the 19th century, during the height of Manifest Destiny, the Mississippi and several western tributaries, most notably the Missouri, formed pathways for pioneers partaking in the western expansion of the United States.

Formed from thick layers of this river's silt deposits, the Mississippi River Valley is one of the most fertile agricultural regions of the country and as a result came the rise of the river's storied steamboat era. During the American Civil War, the Mississippi's capture by Union forces marked a turning point towards victory because of this very importance as a route of trade and travel, not least to the Confederacy. Because of substantial growth of cities, and the larger ships and barges that have supplanted riverboats, the decades following the 1900s saw massive engineering works applied to the river system, such as the often in-combination construction of levees, locks and dams.

Since modern development of the basin began, the Mississippi has also seen its share of pollution and environmental problems – most notably large volumes of agricultural runoff, which has led to the Gulf of Mexico dead zone off the Delta. In recent years, the river has shown a steady shift towards the Atchafalaya River channel in the Delta; a course change would prove disastrous to seaports such as New Orleans. A system of dikes and gates has so far held the Mississippi at bay, but due to fluvial processes the shift becomes more likely each year.