Mississippi River
The Mississippi River is the primary river of the largest drainage basin in the United States. It is the second-longest river in the United States, behind only the Missouri. From its traditional source of Lake Itasca in northern Minnesota, it flows generally south for to the Mississippi River Delta in the Gulf of Mexico. With its many tributaries, the Mississippi's watershed drains all or parts of 32 U.S. states and two Canadian provinces between the Rocky and Appalachian mountains. The river either borders or passes through the states of Minnesota, Wisconsin, Iowa, Illinois, Missouri, Kentucky, Tennessee, Arkansas, Mississippi, and Louisiana. The main stem is entirely within the United States; the total drainage basin is, of which only about one percent is in Canada. The Mississippi ranks as the world's tenth-largest river by discharge flow, and the largest in North America.
Native Americans have lived along the Mississippi River and its tributaries for thousands of years. Many were hunter-gatherers, but some, such as the Mound Builders, formed prolific agricultural and urban civilizations, and some practiced aquaculture. The arrival of Europeans in the 16th century changed the native way of life as first explorers, then settlers, ventured into the basin in increasing numbers. The river served sometimes as a barrier, forming borders for New Spain, New France, and the early United States, and throughout as a vital transportation artery and communications link. In the 19th century, during the height of the ideology of manifest destiny, the Mississippi and several tributaries, most notably its largest, the Ohio and Missouri, formed pathways for the western expansion of the United States. The river also became the subject of American literature, particularly in the writings of Mark Twain.
Formed from thick layers of the river's silt deposits, the Mississippi embayment, and American Bottom are some of the most fertile regions of the United States; steamboats were widely used in the 19th and early 20th centuries to ship agricultural and industrial goods. During the American Civil War, the Mississippi's final capture by Union forces marked a turning point to victory for the Union. Because of the substantial growth of cities and the larger ships and barges that replaced steamboats, the first decades of the 20th century saw the construction of massive engineering works such as levees, locks and dams, often built in combination. A major focus of this work has been to prevent the lower Mississippi from shifting into the channel of the Atchafalaya River and bypassing New Orleans.
Since the 20th century, the Mississippi River has also experienced major pollution and environmental problems, most notably elevated nutrient and chemical levels from agricultural runoff, the primary contributor to the Gulf of Mexico dead zone.
Name and significance
The word Mississippi itself comes from Misi zipi, the French rendering of the Anishinaabe name for the river, Misi-ziibi.In the 18th century, the river was set by the Treaty of Paris as, for the most part, the western border of the new United States. With the Louisiana Purchase and the country's westward expansion, it became a convenient boundary line between the western and eastern halves of the country. This is reflected in the Gateway Arch in St. Louis, which was designed to symbolize the opening of the West, and the focus on the "Trans-Mississippi" region in the Trans-Mississippi Exposition.
Regional landmarks are often classified in relation to the river, such as "the highest peak east of the Mississippi" or "the oldest city west of the Mississippi". The FCC also uses it as the dividing line for broadcast call-signs, which begin with W to the east and K to the west, overlapping in media markets along the river.
Due to its size and importance, it has been nicknamed The Mighty Mississippi River or simply The Mighty Mississippi.
Divisions
The Mississippi River can be divided into three sections: the Upper Mississippi, the river from its headwaters to the confluence with the Missouri River; the Middle Mississippi, which is downriver from the Missouri to the Ohio River; and the Lower Mississippi, which flows from the Ohio to the Gulf of Mexico.Upper Mississippi
The Upper Mississippi runs from its headwaters to its confluence with the Missouri River at St. Louis, Missouri. It is divided into two sections:- The headwaters, from the source to Saint Anthony Falls in Minneapolis, Minnesota; and
- A navigable channel, formed by a series of human-made lakes between Minneapolis and St. Louis, Missouri, some.
The source of the Upper Mississippi branch is traditionally accepted as Lake Itasca, above sea level in Itasca State Park in Clearwater County, Minnesota. The name Itasca was chosen to designate the "true head" of the Mississippi River as a combination of the last four letters of the Latin word for truth and the first two letters of the Latin word for head. However, the lake is in turn fed by a number of smaller streams.
From its origin at Lake Itasca to St. Louis, Missouri, the waterway's flow is moderated by 43 dams. Fourteen of these dams are located above Minneapolis in the headwaters region and serve multiple purposes, including power generation and recreation. The remaining 29 dams, beginning in downtown Minneapolis, all contain locks and were constructed to improve commercial navigation of the upper river. Taken as a whole, these 43 dams significantly shape the geography and influence the ecology of the upper river. Beginning just below Saint Paul, Minnesota, and continuing throughout the upper and lower river, the Mississippi is further controlled by thousands of wing dikes that moderate the river's flow in order to maintain an open navigation channel and prevent the river from eroding its banks.
The head of navigation on the Mississippi is the St. Anthony Falls Lock. Before the Coon Rapids Dam in Coon Rapids, Minnesota, was built in 1913, steamboats could occasionally go upstream as far as Saint Cloud, Minnesota, depending on river conditions.
The uppermost lock and dam on the Upper Mississippi River is the Upper St. Anthony Falls Lock and Dam in Minneapolis. Above the dam, the river's elevation is. Below the dam, the river's elevation is. This drop is the largest of all the Mississippi River locks and dams. The origin of the dramatic drop is a waterfall preserved adjacent to the lock under an apron of concrete. Saint Anthony Falls is the only true waterfall on the entire Mississippi River. The water elevation continues to drop steeply as it passes through the gorge carved by the waterfall.
After the completion of the St. Anthony Falls Lock and Dam in 1963, the river's head of navigation moved upstream, to the Coon Rapids Dam. However, the Locks were closed in 2015 to control the spread of invasive Asian carp, making Minneapolis once again the site of the head of navigation of the river.
The Upper Mississippi has a number of natural and artificial lakes, with its widest point being Lake Winnibigoshish, near Grand Rapids, Minnesota, over across. Lake Onalaska, created by Lock and Dam No. 7, near La Crosse, Wisconsin, is more than wide. Lake Pepin, a natural lake formed behind the delta of the Chippewa River of Wisconsin as it enters the Upper Mississippi, is more than wide.
By the time the Upper Mississippi reaches Saint Paul, Minnesota, below Lock and Dam No. 1, it has dropped more than half its original elevation and is above sea level. From St. Paul to St. Louis, Missouri, the river elevation falls much more slowly and is controlled and managed as a series of pools created by 26 locks and dams.
The Upper Mississippi River is joined by the Minnesota River at Fort Snelling in the Twin Cities; the St. Croix River near Prescott, Wisconsin; the Cannon River near Red Wing, Minnesota; the Zumbro River at Wabasha, Minnesota; the Black, La Crosse, and Root rivers in La Crosse, Wisconsin; the Wisconsin River at Prairie du Chien, Wisconsin; the Rock River at the Quad Cities; the Iowa River near Wapello, Iowa; the Skunk River south of Burlington, Iowa; and the Des Moines River at Keokuk, Iowa. Other major tributaries of the Upper Mississippi include the Crow River in Minnesota, the Chippewa River in Wisconsin, the Maquoketa River and the Wapsipinicon River in Iowa, and the Illinois River in Illinois.
The Upper Mississippi is largely a multi-thread stream with many bars and islands. From its confluence with the St. Croix River downstream to Dubuque, Iowa, the river is entrenched, with high bedrock bluffs lying on either side. The height of these bluffs decreases to the south of Dubuque, though they are still significant through Savanna, Illinois. This topography contrasts strongly with the Lower Mississippi, which is a meandering river in a broad, flat area, only rarely flowing alongside a bluff.
File:CairoIL from space annotated.jpg|thumb|The confluence of the Mississippi and Ohio rivers at Cairo, Illinois, the demarcation between the Middle and the Lower Mississippi River
Middle Mississippi
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 to its confluence with the Ohio River at Cairo, Illinois.The Middle Mississippi is relatively free-flowing. From St. Louis to the Ohio River confluence, the Middle Mississippi falls over for an average rate of. At its confluence with the Ohio River, the Middle Mississippi is above sea level. Apart from the Missouri and Meramec rivers of Missouri and the Kaskaskia River of Illinois, no major tributaries enter the Middle Mississippi River.
Lower Mississippi
The Mississippi River is called the Lower Mississippi River from its confluence with the Ohio River to its mouth at the Gulf of Mexico, a distance of about. At the confluence of the Ohio and the Middle Mississippi, the long-term mean discharge of the Ohio at Cairo, Illinois is, while the long-term mean discharge of the Mississippi at Thebes, Illinois is. Thus, by volume, the main branch of the Mississippi River system at Cairo can be considered to be the Ohio River, rather than the Middle Mississippi.In addition to the Ohio River, the major tributaries of the Lower Mississippi River are the White River, flowing in at the White River National Wildlife Refuge in east-central Arkansas; the Arkansas River, joining the Mississippi at Arkansas Post; the Big Black River in Mississippi; and the Yazoo River, meeting the Mississippi at Vicksburg, Mississippi.
Deliberate water diversion at the Old River Control Structure in Louisiana allows the Atchafalaya River in Louisiana to be a major distributary of the Mississippi River, with 30% of the combined flow of the Mississippi and Red Rivers flowing to the Gulf of Mexico by this route, rather than continuing down the Mississippi's current channel past Baton Rouge and New Orleans on a longer route to the Gulf. Although the Red River was once an additional tributary, its water now flows separately into the Gulf of Mexico through the Atchafalaya River.