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Mississippi River
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Mississippi River

This page is about the river in the United States; for other uses, see Mississippi River (disambiguation).

The Mississippi River is the second longest river in the United States. The longest is the Missouri River, which flows into the Mississippi River. Taken together, they form the largest river system in North America. If measured from the head of the Missouri, the length of the Missouri/Mississippi combination is approximately 3,895 miles (6,270 km) long.

Table of contents
1 Geography
2 History
3 Major cities along the river
4 Notable Bridges
5 External links

Geography

With its source Lake Itasca at 1475 feet above sea level in Itasca State Park in northern Minnesota, the river falls to 725 feet just below Saint Anthony Falls in Minneapolis. The Mississippi is joined by the Illinois River and the Missouri River at Saint Louis, and by the Ohio at Cairo, Illinois.

The Mississippi drains most of the area between the Rocky Mountains and the Appalachian Mountains, except for the area drained by the Great Lakes. It runs through, or borders, ten states in the United States -- Minnesota, Wisconsin, Iowa, Illinois, Missouri, Kentucky, Arkansas, Tennessee, Mississippi and Louisiana -- before emptying into the Gulf of Mexico about 100 miles (160 km) downstream from New Orleans. A raindrop falling in Lake Itasca would arrive at the Gulf of Mexico in about 90 days. [1]

The river is divided into the upper Mississippi, from its source south to the Ohio River, and the lower Mississippi, from the Ohio to its mouth near New Orleans. The upper Mississippi is further divided into three sections: the headwaters, from the source to St. Anthony Falls, a series of man-made lakes between Minneapolis and St. Louis, and the middle Mississippi, a relatively free-flowing river downstream of the confluence with the Missouri River at St. Louis.

A series of 27 locks and dams on the upper Mississippi, most of which were built in the 1930s, is designed primarily to maintain a nine-foot channel for commercial barge traffic. The lakes formed are also used for recreational boating and fishing. The dams make the river deeper and wider but do not stop it. No flood control is intended. During periods of high flow, the gates, some of which are submersible, are completely opened and the dams simply cease to function. Below St. Louis the Mississippi is relatively free flowing although it is constrained by numerous levies and directed by numerous wing dams.

The mouth of the Mississippi River has shifted repeatedly over time. Since a canal was built in the early nineteenth century, the river has been seeking the Atchafalaya River mouth, some 60 miles (95 km) from New Orleans. The U.S. Army Corps of Engineers maintains a massive system of locks to keep the river in its present course.

Other changes in the course of the river have occurred because of earthquakes along the New Madrid Fault Zone, which lies near the cities of Memphis and St. Louis. Three earthquakes in 1811 and 1812, estimated at approximately 8 on the Richter Scale, were said to have temporarily reversed the course of the Mississippi. These earthquakes also created Reelfoot Lake in Tennessee from the altered landscape near the river. The faulting is related to an aulacogen (geologic term for a failed rift) that formed at the same time as the Gulf of Mexico.

Davenport, Iowa is the only city over 20,000 people bordering the Mississippi that has no permanent floodwall or levee.

Watershed

The Mississippi River has the third largest drainage basin in the world, exceeded in size only by the watersheds of the Amazon River and Congo River. It drains 41 percent of the 48 contiguous states of the United States. The basin covers more than 1,245,000 square miles (3,225,000 km˛), including all or parts of 31 states and two Canadian provinces.

History

The word Mississippi comes from the Ojibwe name for the river, "Messipi", which means big river.

On May 8, 1541 Hernando de Soto became the first recorded white man to reach the Mississippi River, which he called "Rio de Espiritu Santo" (River of the Holy Spirit). French explorers Louis Joliet and Jacques Marquette began exploring the Mississippi, which they knew by the Sioux name "Ne Tongo" (which, like the Ojibwe name, means big river), on May 17, 1673. In 1682, René Robert Cavelier, Sieur de La Salle and Henri de Tonty claimed the entire Mississippi River Valley for France, calling it Louisiana, for King Louis XIV.

The Treaty of Paris (1763) gave England rights to all land in the valley east of the Mississippi, and Spain rights to land west of the Mississippi. France re-acquired 'Louisiana' in the secret Treaty of San Ildefonso in 1800. The United States bought the territory from France in the Louisiana Purchase of 1803.

The river was noted for the number of bandits which called its islands and shores home, including John Murrell who was a well-known murderer, horse stealer and slave "re-trader." His notoriety was such that author Mark Twain devoted an entire chapter to him in his book Life on the Mississippi, and Murrell was rumored to have an island headquarters on the river at Island 37.

Twain's book also extensively covered the thrilling steamboat races which took place from 1830 to 1870 on the river before more modern boating methods replaced the steamer. It was published first in serial form in Harper's Weekly in seven parts in 1875 and was intended to chronicle the rapidly disappearing steamboat culture. The full version, including a passage from the unfinished Huckleberry Finn and works from other authors, was published by James R. Osgood & Co; in 1885. The first steamboat to travel the full length of the Mississippi from the Ohio River to the city of New Orleans, Louisiana was the New Orleans in December 1811. Its maiden voyage occurred during the series of New Madrid earthquakes in 1811-1812.

In the spring of 1927 the river broke out of its banks in 145 places during the Great Mississippi Flood of 1927 and inundated 27,000 square miles (70,000 km²) to a depth of up to 30 feet (10 m).

The Great Flood of 1993 is considered the most devastating flood to occur in the U.S. in modern history.

In 2002 Martin Strel swam the entire length of the river.

Maintaining a Navigation Channel

The task of maintaining a navigation channel on the Mississippi is the responsibility of the U.S. Army Corps of Engineers, which began as early as 1829 removing snags, closing off secondary channels and excavating rocks and sandbars. In 1829 the Corps surveyed the two major obstacles on the upper Mississippi, the Des Moines Rapids and the Rock Island Rapids, where the river was shallow and the riverbed was rock. The Des Moines Rapids were about 11 miles long and just above the mouth of the Des Moines River at Keokuk. The Rock Island Rapids were between Rock Island and Moline. Both rapids were considered virtually impassable.

The Corp recommended excavation of a 5 foot channel at the Des Moines Rapids, but work didn't begin until after Lieutenant Robert E. Lee endorsed the project in 1837. The Corps later also began excavating the Rock Island Rapids. By 1866 it had become evident that excavation was impractical, and it was decided build a canal around the Des Moines Rapids. The canal opened in 1877, but the Rock Island Rapids remained an obstacle.

In 1878, Congress authorized the Corps to establish a 4-1/2-foot channel, to be obtained by building wing dams which direct the river to a narrow channel causing it to cut a deeper channel, closing secondary channels, and by dredging. The 4-1/2 foot channel project was complete when the Moline Lock, which bypassed the Rock Island Rapids, opened in 1907.

To improve navigation between St. Paul and Prairie du Chien, the Corps constructed several dams on lakes in the headwaters area, including Lake Winnibigoshish and Lake Pokegama. The dams, which were built beginning in the 1880s, stored spring run-off, which was released during low water to help maintain channel depth.

A ship canal connecting the Illinois River with Lake Michigan was completed in 1900. This provided a link between the Mississippi River and the Great Lakes.

In 1907, Congress authorized a six-foot channel project on the Mississippi, which wasn't complete when it was abandoned in the late 1920s in favor of the nine-foot channel project.

In 1913, construction was complete on a dam at Keokuck, the first dam below St. Anthony Falls. Built by a private power company to generate electricity, the Keokuk dam was one of the largest hydro-electric plants in the world at the time. The dam also eliminated the Des Moines Rapids.

Lock and Dam No. 1 was completed in Minneapolis in 1917 and Lock and Dam No. 2 at Hastings, Minnesota, was completed in 1930.

The Rivers and Harbors Act of 1930 authorized the 9-foot channel project, which called for a navigation channel 9 feet deep and 400 feet wide to accommodate multiple-barge tows. This was achieved by a series of locks and dams, and by dredging. Twenty-three new locks and dams were built on the upper Mississippi in the 1930s in addition to the three already in existence.

Until the 1950s, there was no dam below Lock and Dam 26 at Alton, Illinois. Lock and Dam 27, which consists of a low-water dam and an 8.4 mile long canal, was added in 1953 just below the confluence with the Missouri River, primarily to bypass a series of rock ledges at St. Louis, but also to protect the St. Louis city water intakes during times of low water.

Dam 26 at Alton, Illinois, which had structural problems, was replaced by the Mel Price Lock and Dam in 1990. The original Lock and Dam 26 was demolished.

Major cities along the river

Notable Bridges

External links

See also Mississippi Delta; Mississippi River (Ontario).