Mississippi River
North America's great central artery, from Minnesota to the Gulf
The Mississippi gathers the runoff of nearly half the continental United States and funnels it to the Gulf of Mexico through a single muddy channel. From a modest outlet at Lake Itasca in northern Minnesota it grows into a continental drain, swelled by the Missouri and Ohio into one of the great river systems on Earth. It has shaped American settlement, commerce and imagination, the highway down which the country's heartland reaches the sea.
Hydrologists count the Mississippi proper at roughly 3,766 kilometers, though joined with the Missouri it forms a system rivaling the longest in the world. The river is fed by a drainage basin spanning thirty-one states and two Canadian provinces. Below the confluence with the Ohio at Cairo it becomes a broad, sediment-heavy lowland river, hemmed by levees and prone to enormous floods. At its mouth it has built a bird-foot delta of shifting mud, constantly extended by sediment and constantly eroded by the sea and subsidence.
For more than a century the river was the spine of American trade, carrying cotton, grain and steamboats — Mark Twain made its piloting culture legendary. The Army Corps of Engineers now manages it with an elaborate system of locks, dams and levees that keep barges moving and cities dry, though the 1927 and 1993 floods showed the limits of that control. The delta wetlands at its mouth are vanishing, and the river's nutrient load feeds a vast low-oxygen dead zone in the Gulf each summer.