Mississippi River is one of the chief rivers of North America and the second longest river in the United States. Only the Missouri is longer. The Mississippi flows 2,340 miles (3,766 kilometers) from its source in northwestern Minnesota to its mouth in the Gulf of Mexico. The Mississippi and its tributaries drain almost all the plains that lie between the Appalachian Mountains and the Rocky Mountains. This drainage basin covers 1,247,300 square miles (3,230,490 square kilometers) and includes the nation’s most productive agricultural and industrial areas.
The Mississippi is the nation’s chief inland waterway. It carries agricultural goods, industrial products, and raw materials. Ships can travel the river for more than 1,800 miles (2,897 kilometers) from Minneapolis, Minn., to the Gulf of Mexico. The river ranges in depth from 9 feet (2.7 meters) to 100 feet (30 meters) during most of its course. The river reaches its widest point—about 31/2 miles (5.6 kilometers)—just north of Clinton, Iowa, in a backwater formed by Lock and Dam No. 13.
The Mississippi, which is sometimes called “Old Man River,” has played a vital role in the history of the United States. During the 1500’s and 1600’s, it provided a route for Spanish and French explorers. With the coming of steamboats in the 1800’s, the Mississippi became a great transportation and trade route. The famous American author Mark Twain described the river vividly in his book Life on the Mississippi (1883).
The course of the Mississippi.
The Mississippi begins as a small, clear stream that rushes out of Lake Itasca in northwestern Minnesota. The river flows northward and then eastward, linking a series of lakes. 
The Mississippi begins to curve southward near Grand Rapids, Minn. As it flows between Minneapolis and St. Paul, Minn., it is joined by the Minnesota River. Beginning with its junction with the St. Croix River, the Mississippi forms part of the boundary between Minnesota and Wisconsin. It is also part of the boundaries of eight other states. Illinois, Kentucky, Tennessee, and Mississippi are to the east, and Iowa, Missouri, Arkansas, and part of Louisiana are on the western shore.
Two major tributaries, the Illinois River and the Missouri River, join the Mississippi above St. Louis. The muddy waters of the Missouri mix with the clear waters of the Mississippi, and the Mississippi takes on the muddy color for which it is known in the South.
The Ohio River flows into the Mississippi at Cairo, Illinois, doubling the Mississippi’s volume of water. This junction divides the upper Mississippi from the lower Mississippi. South of Cairo, the flood plain of the Mississippi forms a fertile valley. The valley is over 50 miles (80 kilometers) wide in some places. The river winds back and forth through this valley and forms broad loops. It sometimes changes its course and cuts off the loops, creating horseshoe-shaped lakes called oxbow lakes. Along its lower course, the Mississippi deposits soil particles called silt along its banks. The silt builds up and forms embankments known as natural levees.
The Arkansas River joins the Mississippi about 50 miles (80 kilometers) north of Greenville, Mississippi. North of Marksville, Louisiana, the Red River enters the Mississippi flood plain, but most of its flow continues into the Atchafalaya River. About a fourth of the Mississippi’s water also goes into the Atchafalaya.
As the Mississippi approaches the Gulf of Mexico, it deposits large amounts of silt to form a delta. The Mississippi Delta covers about 13,000 square miles (33,700 square kilometers). South of New Orleans, the river breaks up into several channels called distributaries, which enter the Gulf of Mexico. They include Main Pass, North Pass, South Pass, and Southwest Pass. The Mississippi River system empties over 640, 000 cubic feet (18,100 cubic meters) of water per second into the gulf. This discharge totals about 133 cubic miles (554 cubic kilometers) of water per year.
Commerce.
The Mississippi River carries about half of the freight that is transported on the nation’s inland waterways. About 500 million short tons (450 million metric tons) of freight are transported on the Mississippi annually.
Most commercial freight on the Mississippi travels on large barges pushed by tugboats. Between Minneapolis and Cairo, the southbound freight consists mainly of agricultural products, such as corn, soybeans, and wheat. Coal and steel products from the Ohio River system are transported north. South of Cairo, goods from the Ohio double the Mississippi’s traffic. Most of the cargo consists of southbound agricultural goods, coal, and steel products. At Baton Rouge, Louisiana, petrochemical products, aluminum, and petroleum are added to the barge traffic. Beginning at Baton Rouge, the Mississippi deepens and allows passage of oceangoing vessels. The greatest volume of traffic on the Mississippi moves between New Orleans and Southwest Pass.
Floods and flood control.
From time to time, the Mississippi has caused serious floods. The floods occur when rain and melting snow bring unusually large amounts of water into the Mississippi. The river then overflows into the surrounding flood plain. Especially destructive floods occurred in 1927, 1937, 1965, 1973, 1982, 1983, and 1993. The most destructive of these was the 1993 flood. See Flood.
Dams and levees have provided some protection against flooding by the Mississippi River. A series of dams along the Missouri and Ohio rivers control the amount of water that enters the Mississippi. The Mississippi itself was dammed north of St. Louis. Along the lower course of the Mississippi, the natural levees have been heightened and new levees built to prevent flooding. Dredging of the river channel not only increases the amount of water the river can carry, but also aids navigation on the river. In addition, areas of land that are called floodways provide outlets for draining off water when the river reaches flood level.
Animal and plant life.
The Mississippi River and its valley support many kinds of animals and plants. Such freshwater fishes as bass, sunfish, and trout live in the clear waters of the upper Mississippi. Carp, catfish, and buffalo fish are found in the muddy waters of the lower Mississippi.
The most common animals in the Mississippi Valley are mink, muskrats, opossums, otters, and skunks. Large rodents called nutrias live in the swamps and marshlands of the delta area (see Nutria ). This area also provides winter nesting grounds for ducks, geese, and other migratory birds. Pelicans, herons, and egrets live in the area throughout the year.
Forests of hardwood trees, such as basswood, hickory, maple, and oak, grow in the upper Mississippi Valley. South of Cairo, the forests consist mainly of baldcypress, sweet gum, southern oak, and tupelo trees.
Pollution seriously threatens the wildlife of the Mississippi. Fertilizers and insecticides used on farms are washed into the river, and industries empty wastes into its waters. Since the 1970’s, steps have been taken to prevent further pollution of the river. For example, federal regulations prohibit farmers from using certain insecticides and other harmful chemicals.
History.
The Mississippi was formed about 2 million years ago at the beginning of the Pleistocene Epoch, a time marked by a succession of ice ages, which ended about 11,500 years ago. During this period, glaciers covered much of the Northern Hemisphere. Melting ice from the glaciers was carried to the Mississippi by both the Missouri and Ohio rivers.
Various Indian tribes, including the Illinois, the Kickapoo, the Ojibway, and the Santee Dakota, lived in the upper Mississippi Valley. The name Mississippi, which means big river, came from these tribes. The lower valley was the home of such tribes as the Chickasaw, the Choctaw, the Natchez, and the Tunica.
The first European to travel on the Mississippi was the Spanish explorer Hernando de Soto. He crossed the river in 1541 near what is now Memphis. In the early 1680’s, the French explorer Sieur de La Salle traveled on the river and claimed the Mississippi Valley for France.
France lost all of its territories on the mainland of North America as a result of the French and Indian War (1754-1763). Britain (now the United Kingdom) gained the land east of the Mississippi, and Spain took over the land west of the river. After the Revolutionary War in America (1775-1783), the United States took control of the British territories. In 1800, France regained the land west of the Mississippi. The United States bought this land from France in the Louisiana Purchase of 1803.
After the entire Mississippi Valley became part of the United States, settlers and traders set out on the river in flatboats, keelboats, and rafts. The importance of the river as a transportation and trade route increased with the development of steamboats in the early 1800’s. Mississippi River cities, including St. Louis, Memphis, and New Orleans, served as supply centers for the westward movement. 
During the American Civil War (1861-1865), the Mississippi served as an invasion route for the Union forces. The capture of such river cities as New Orleans, Memphis, and Vicksburg, Mississippi, divided the Confederacy in half and assured victory for the North. After the war, railroads soon took over most of the river’s former steamboat traffic. The completion of the Eads Bridge in 1874, connecting St. Louis and East St. Louis, Illinois, provided a major rail crossing over the river. Many more bridges were built during the years that followed.
The importance of the Mississippi as a transportation route has increased greatly since the 1920’s. No other means of transportation can move masses of heavy, bulky cargo as cheaply as the barges and tugboats on the mighty river.
