Jefferson River

The Jefferson River is a tributary of the Missouri River, approximately 77 miles (124 km) long, in the U.S. state of Montana.

The Jefferson River and the Madison River form the official beginning of the Missouri at Missouri Headwaters State Park near Three Forks. It is joined 0.6 miles (1.0 km) downstream (northeast) by the Gallatin.

The Lewis and Clark Expedition visited the site on 28 July 1805. Meriwether Lewis in his journal entry wrote:

Both Capt. C. and myself corresponded in opinon with rispect[sic] to the impropriety of calling either of these [three] streams the Missouri and accordingly agreed to name them after the President of the United States and the Secretaries of the Treasury and State.

The Lewis and Clark decision not to call the Jefferson (named for President Thomas Jefferson) the Missouri has spurred debate over what is the longest river in North America since the Missouri and Mississippi are nearly identical in length. The Missouri traditionally had been called the longest river on the continent. However, 72 miles (116 km) of it have been trimmed off in channeling so that it is now sometimes referred as second to the Mississippi in terms of length. If the Jefferson were included in the Missouri length, it would still be considered the longest river.

The utmost headwaters of the Missouri are subject to debate, but both locations ultimately drain into the Jefferson. Lewis on August 12, 1805, said he visited the headwaters on Trail Creek just above Lemhi Pass on the Continental Divide in the Beaverhead Mountains at around 8,600 feet (2,600 m) which he described:

the most distant fountain of the waters of the mighty Missouri in surch[sic] of which we have spent so many toilsome days and wristless[sic] nights.

However in 1888 Jacob V. Brower, who had championed turning the headwaters of the Mississippi River into a Minnesota state park, visited another site which today is believed to be the furthest point on the Missouri — now called Brower's Spring. Brower published his finding in 1896 in "The Missouri: Its Utmost Source."

Brower's Spring lies at around 8,800 feet (2,700 m) in the Centennial Mountains. The site is marked by a rock pile at the source of Hell Roaring Creek which flows into Red Rock River. The Red Rock River rises in the Centennial Mountains near the Continental Divide in southwestern Beaverhead County, near Montana's border with Idaho, also the Continental Divide.

It flows west through Upper and Lower Red Rock lakes, then NNW past Lima to the Clark Canyon Reservoir, where it becomes the Beaverhead River. As the Beaverhead, the river flows NNE past Dillon. Near Twin Bridges, the Beaverhead is joined by the Ruby River and the Big Hole River, and continues as the Jefferson River north and east. Near Cardwell, it receives the Boulder River, and flows east to form the Missouri where it meets the Madison and Gallatin northeast of Three Forks, approximately 28 miles (45 km) WNW of Bozeman.

The river is a Class I water from its origin at the Beaverhead and Big Hole rivers to its confluence with the Missouri at Three Forks for the purposes of public access for recreational purposes.

Geology of the Missouri River

The Rocky Mountains of southwestern Montana at the headwaters of the Missouri River first rose in the Laramide Orogeny, a mountain-building episode that occurred from around 70 to 45 million years ago (the end of the Mesozoic through the early Cenozoic). This orogeny uplifted Cretaceous rocks along the western side of the Western Interior Seaway, a vast shallow sea that stretched from the Arctic Ocean to the Gulf of Mexico, and deposited the sediments that now underlie much of the drainage basin of the Missouri River. This Laramide uplift caused the sea to retreat and laid the framework for a vast drainage system of rivers flowing from the Rocky and Appalachian Mountains, the predecessor of the modern-day Mississippi watershed. The Laramide Orogeny is essential to modern Missouri River hydrology, as snow and ice melt from the Rockies provide the majority of the flow of the Missouri and its tributaries.

The Missouri and many of its tributaries cross the Great Plains, flowing over or cutting into the Ogallala Group and older mid-Cenozoic sedimentary rocks. The lowest major Cenozoic unit, the White River Formation, was deposited between approximately 35 and 29 million years ago and consists of claystone, sandstone, limestone, and conglomerate. Channel sandstones and finer-grained overbank deposits of the fluvial Arikaree Group were deposited between 29 and 19 Million years ago. The Miocene-age Ogallala and the slightly younger Pliocene-age Broadwater Formation deposited atop the Arikaree Group, and are formed from material eroded off of the Rocky Mountains during a time of increased generation of topographic relief; these formations stretch from the Rocky Mountains nearly to the Iowa border and give the Great Plains much of their gentle but persistent eastward tilt, and also constitute a major aquifer.

Immediately prior to the Quaternary Ice Age, the Missouri River was likely split into three segments: an upper portion that drained northwards into Hudson Bay, and middle and lower sections that flowed eastward down the regional slope. As the Earth plunged into the Ice Age, a pre-Illinoian (or possibly the Illinoian) glaciation diverted the Missouri River southeastwards towards its present confluence with the Mississippi and caused it to integrate into a single river system that cuts across the regional slope.

Nicknamed the “Big Muddy”, the Missouri certainly lives up to this name, carrying 20,000,000 to 25,000,000 short tons (18,000,000 to 23,000,000 t) of sediment per year. Before the construction of dams and levees, this load was 13-16 times higher, averaging 320,000,000 short tons (290,000,000 t) per year.Much of this sediment is derived from the river’s floodplain, also called the meander belt; every time the river changed course, it would erode tons of soil and rocks from its banks. However, channeling and diking the river has kept it from reaching its natural sediment sources along most of its course. Also, the creation of giant reservoirs has trapped millions of tons of sediment since the 1950s. Despite this, the river still transports more than half the total silt that empties into the Gulf of Mexico; the Mississippi River Delta, formed by sediment deposits at the mouth of the Mississippi, constitutes a majority of sediments carried by the Missouri.

Watershed of the Missouri River

With a drainage basin spanning 529,350 square miles (1,371,000 km²), the Missouri's catchment encompasses nearly one-sixth of the area of the United States or just over 5% of the continent of North America. The mostly flat, arid basin, comparable to the size of the Canadian province of Quebec, encompasses most of the northern Great Plains, stretching over 1,500 miles (2,400 km) from the Rocky Mountains in the west to the Mississippi River valley in the east. From north to south it reaches well over 1,600 miles (2,600 km), from the U.S.-Canada border in the north to the Arkansas River valley of the south. Compared with the Mississippi River above their confluence, the Missouri is actually much longer and drains a greater area. However, the flow of the Missouri at the confluence accounts for only 45% of the total amount of water below the meeting of the rivers.

Although vast, the Missouri River watershed is home to only about 10 million people, living in all of the U.S. state of Nebraska, parts of the U.S. states of Colorado, Iowa, Kansas, Minnesota, Missouri, Montana, North Dakota, South Dakota, and Wyoming, and small southern portions of the Canadian provinces of Alberta and Saskatchewan. Significant tributary systems within the basin include the Milk and Yellowstone in the northwest, the James and Osage of the east, and the Platte and Kansas-Republican/Smoky Hill drainages of the southwestern plains. The Platte is the longest tributary, but the Yellowstone River is the largest tributary by discharge (in fact the Yellowstone's flow is about 13,800 cubic feet per second (390 m³/s) while the Platte averages a comparatively mere 7,000 cubic feet per second (200 m³/s)).

Elevations in the watershed vary widely from just over 400 feet (120 m) at the Missouri's mouth to 12,000 to 14,500 feet (3,700 to 4,400 m) in the heights of the Rockies in Montana, Wyoming and Colorado. The river itself drops from over 9,000 feet (2,700 m) in elevation at Brower's Spring, the farthest source. Although the plains of the watershed appear flat to the eye, there is a definite slope from west to east; the land is roughly 3,000 feet (910 m) above sea level at the base of the Rockies, but less than 500 feet (150 m) at the border of the Mississippi valley. Mount Elbert, in Colorado, is the highest peak in the Missouri watershed at 14,433 feet (4,399 m) and is the 2nd highest in the Continental United States.

As one of the continent's most important rivers, the Missouri's drainage basin borders on many other major watersheds of the United States and Canada. The Columbia River and Colorado River systems drain the area west of the Rocky Mountains; however, in Wyoming, between the Missouri and Colorado watersheds there is a 3,900-square-mile (10,000 km²) endorheic drainage called the Great Divide Basin, that does not have an outlet to the sea. On the north it is bounded by the Saskatchewan and Red River of the North, as well as several large endorheic areas in southern Alberta, Saskatchewan and northeastern North Dakota. On the east it is bordered by the upper Mississippi River and its western tributaries, and to the south by the Arkansas and White watersheds.

Course of the Missouri River

The Missouri River rises in the Rocky Mountains of southwestern Montana at the confluence of the Jefferson River and Madison River, in Missouri Headwaters State Park near the town of Three Forks. It flows north, passing through Canyon Ferry Lake, west of the Big Belt Mountains. It exits from the mountains near Cascade, and flows northeast to the city of Great Falls, where it drops over the Great Falls of the Missouri, a series of five substantial cataracts. The Missouri then flows east through canyons and badlands, past the confluence with the Marias River, widening into the Fort Peck Lake reservoir near the confluence of the Musselshell River. Farther on the river passes through the gates of the Fort Peck Dam, and immediately after that, the Milk River enters from the left.

It flows eastwards through the plains of eastern Montana, receiving the Poplar River at Poplar before crossing into North Dakota where the Yellowstone River, its greatest tributary, joins from the right. At the confluence, the two rivers are approximately the same size. The Missouri then meanders east past Williston and into Lake Sakakawea, a reservoir formed by the Garrison Dam, where the river turns south. South of Riverdale, the Knife River enters from the right. The Missouri continues south to the city of Bismarck, the North Dakota state capital, where it receives the Heart River. It slows into the Lake Oahe reservoir just before the Cannonball River confluence. While it continues south, eventually reaching Oahe Dam in South Dakota, the Grand, Moreau and Cheyenne Rivers all join the Missouri from the right.

The Missouri makes a bend to the southeast as it meanders through the Great Plains, receiving the Niobrara River from the right. The Missouri then proceeds to form the boundary of South Dakota and Nebraska, then after it receives the James River, forms the Iowa-Nebraska boundary. At Sioux City the Big Sioux River comes in from the left. The Missouri flows south to the big city of Omaha where it receives one of its largest tributaries, the Platte River. Downstream of there, it begins to define the Nebraska-Missouri border, then flows between Missouri and Kansas. It turns east at Kansas City, where the Kansas River enters from the right, and so on into north-central Missouri. The river passes south of Columbia and receives the Osage River, its last major tributary, downstream of Jefferson City. It then rounds the northern side of St. Louis to join the Mississippi River on the border between Missouri and Illinois.

Missouri River

The Missouri River is a major river of central North America, and is a tributary of the Mississippi River. It is the longest river by name on the continent at 2,341 miles (3,767 km), and the second largest tributary of the Mississippi by discharge, after the Ohio. The watershed of the Missouri River drains nearly 530,000 square miles (1,400,000 km²) of the Great Plains east of the Rocky Mountains, spanning parts of ten U.S. states and two Canadian provinces. Around 10 million people live in the basin, many concentrated in urban centers along the main stem such as St. Louis; Kansas City; Omaha; Sioux City; and Great Falls. Measured from its hydrologic source in the Centennial Mountains of Montana to the Mississippi's mouth at the Gulf of Mexico, it forms part of the fourth-longest river system in the world.

As early as 12,000 years ago, Paleo-Indians settled in the plains of the Missouri River basin. Prominent Native American tribes that lived on the river in immediate pre-Columbian times included the Mandan, Sioux, Hidatsa, Osage, and Missouria – the latter for whom the river is named. European and American explorers wandered the region in the 1700s and 1800s, when the Missouri basin became part of France's Louisiana territory. When Louisiana was sold to the United States, the Lewis and Clark Expedition traveled the river in search of a route to the Pacific coast of North America. Settlers' expansion into the Great Plains pushed Native Americans out of their traditional lands, leading to wars. The Missouri River served as a boundary for the American frontier in the 19th century, and many prominent westward routes such as the Oregon Trail had their starting points on the river.

Although it once was by far the longest river of North America, today its length is comparable with the Mississippi because of channelization to eliminate meanders and facilitate navigation. The lower Missouri valley has become a highly productive agricultural and industrial region. Barges shipping gravel, wheat, fertilizer, and other grown, mined or manufactured products provide most river commerce today. In response to the growing amount of water traffic, federal and state agencies including the U.S. Army Corps of Engineers (USACE) heavily dammed and channelized the river in the 20th century. Although this development has contributed to the region's economic growth, it has taken a toll on the ecology and the water quality of the Missouri.

Navigation and Flood Control Missisippi River

A clear channel is needed for the barges and other vessels that make the main stem Mississippi one of the great commercial waterways of the world. The task of maintaining a navigation channel is the responsibility of the United States Army Corps of Engineers, which was established in 1802. Earlier projects began as early as 1829 to remove snags, close off secondary channels and excavate rocks and sandbars.

Steamboats entered trade in the 1820s, so the period 1830 – 1850 became the golden age of steamboats. As there were few roads or rails in the lands of the Louisiana Purchase, river traffic was an ideal solution. Cotton, timber and food came down the river, as did Appalachian coal. The port of New Orleans boomed as it was the trans-shipment point to deep sea ocean vessels. As a result, the image of the twin stacked, wedding cake Mississippi steamer entered into American mythology. Steamers worked the entire route from the trickles of Montana, to the Ohio river; down the Missouri and Tennessee, to the main channel of the Mississippi. Only the arrival of the railroads in the 1880s did steamboat traffic diminish. Steamboats remained a feature until the 1920s. Most have been superseded by pusher tugs. A few survive as icons—the Delta Queen and the River Queen for instance.

A series of 29 locks and dams on the upper Mississippi, most of which were built in the 1930s, is designed primarily to maintain a 9 feet (2.7 m) deep 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 levees and directed by numerous wing dams.

Barges on the Mississippi River near Ste. Genevieve, Missouri.

21st Century

In 2002, Slovenian long-distance swimmer Martin Strel swam the entire length of the river, from Minnesota to Louisiana, over the course of 68 days.

In 2005, the Source to Sea Expedition paddled the Mississippi and Atchafalaya Rivers to benefit the Audubon Society's Upper Mississippi River Campaign.

On August 1, 2007, the I-35W Mississippi River bridge in Minneapolis collapsed during the evening rush hour.

Extensive flooding in April and May 2011 was compared to the Great Mississippi Flood of 1927 and the Great Mississippi and Missouri Rivers Flood of 1993.

20th Century

The "Big Freeze" of 1918/19 blocked river traffic north of Memphis, Tennessee, preventing transportation of coal from southern Illinois. This resulted in widespread shortages, high prices, and rationing of coal in January and February.

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 sq mi (70,000 km²) to a depth of up to 30 ft (9.1 m).

On October 20, 1976, the automobile ferry, MV George Prince, was struck by a ship traveling upstream as the ferry attempted to cross from Destrehan, Louisiana, to Luling, Louisiana. Seventy-eight passengers and crew died; only eighteen survived the accident.

In 1988, record low water levels provided an opportunity and obligation to examine the climax of the wooden-hulled age. The Mississippi fell to 10 feet (3.0 m) below zero on the Memphis gauge. Water craft remains were exposed in an area of 4.5 acres (18,000 m²) on the bottom of the Mississippi River at West Memphis, Arkansas. They dated to the late 19th to early 20th centuries. The State of Arkansas, the Arkansas Archeological Survey, and the Arkansas Archeological Society responded with a two-month data recovery effort. The fieldwork received national media attention as good news in the middle of a drought.

The Great Flood of 1993 was another significant flood, primarily affecting the Mississippi above its confluence with the Ohio River at Cairo, Illinois.

Two portions of the Mississippi were designated as American Heritage Rivers in 1997: the lower portion around Louisiana and Tennessee, and the upper portion around Iowa, Illinois, Minnesota and Missouri.

Civil War

Control of the river was a strategic objective of both sides in the American Civil War. In 1862 Union's forces coming down the river successfully cleared Confederate defenses at Island Number 10 and Memphis, Tennessee, while Naval forces coming upriver from the Gulf of Mexico captured New Orleans, Louisiana. The remaining major Confederate stronghold was on the heights overlooking the river at Vicksburg, Mississippi, and the Union's Vicksburg Campaign (December 1862 to July, 1863), and the fall of Port Hudson, completed control of the lower Mississippi River. The Union victory ending the Siege of Vicksburg on July 4, 1863 was pivotal to the Union's final victory of the Civil War.

Steamboat Commerce

Mark Twain's book, Life on the Mississippi, covered the steamboat commerce which took place from 1830 to 1870 on the river before more modern ships replaced the steamer. The book was published first in serial form in Harper's Weekly in seven parts in 1875. The full version, including a passage from the unfinished Adventures of Huckleberry Finn and works from other authors, was published by James R. Osgood & Company in 1885.

The first steamboat to travel the full length of the Mississippi from the Ohio River to New Orleans was the New Orleans in December 1811. Its maiden voyage occurred during the series of New Madrid earthquakes in 1811–12.

Steamboat transport remained a viable industry, both in terms of passengers and freight until the end of the first decade of the 20th century. Among the several Mississippi River system steamboat companies was the noted Anchor Line, which, from 1859 to 1898, operated a luxurious fleet of steamers between St. Louis and New Orleans.

Breaching the Continental Divide

When Louis Jolliet explored the Mississippi Valley in the 17th century, natives guided him to a quicker way to return to French Canada via the Illinois River. When he found the Chicago Portage, he remarked that a canal of "only half a league" (less than 2 miles (3.2 km), 3 km) would join the Mississippi and the Great Lakes. In 1848, the continental divide separating the waters of the Great Lakes and the Mississippi Valley was breached by the Illinois and Michigan canal via the Chicago River. This both accelerated the development, and forever changed the ecology of the Mississippi Valley and the Great Lakes.

New Madrid Earthquakes

Three earthquakes in 1811 and 1812, estimated at approximately 8 on the Richter magnitude scale, were centered neqr New Madrid, Missouri. These earthquakes created Reelfoot Lake in Tennessee from the altered landscape near the river, and were said to have temporarily reversed the direction of flow of the Mississippi itself. The faulting, along the New Madrid Seismic Zone between Memphis and St. Louis, is related to an aulacogen (geologic term for a failed rift) that formed at the same time as the Gulf of Mexico.

19th Century

France reacquired 'Louisiana' from Spain in the secret Treaty of San Ildefonso in 1800. The United States bought the territory from France in the Louisiana Purchase of 1803. In 1815, the U.S. defeated Britain at the Battle of New Orleans, part of the War of 1812, securing American control of the river.

So many settlers traveled westward through the Mississippi river basin, as well as settled in it, that Zadok Cramer wrote a guide book called The Navigator, detailing the features and dangers and navigable waterways of the area. It was so popular that he updated and expanded it through 12 editions over a period of 25 years.

18th Century

Following Britain's victory in the Seven Years War the Mississippi became the border between the British and Spanish Empires. The Treaty of Paris (1763) gave Great Britain rights to all land east of the Mississippi and Spain rights to land west of the Mississippi. Spain also ceded Florida to Britain to regain Cuba, which the British occupied during the war. Britain then divided the territory into East and West Florida.

Article 8 of the Treaty of Paris (1783) states, "The navigation of the river Mississippi, from its source to the ocean, shall forever remain free and open to the subjects of Great Britain and the citizens of the United States". With this treaty, which ended the American Revolutionary War, Britain also ceded West Florida back to Spain to regain The Bahamas, which Spain had occupied during the war. In 1800, under duress from Napoleon of France, Spain ceded an undefined portion of West Florida to France. When France then sold the Louisiana Territory to the US in 1803, a dispute arose again between Spain and the US on which parts of West Florida exactly had Spain ceded to France, which would in turn decide which parts of West Florida were now US property versus Spanish property. These aspirations ended when Spain was pressured into signing Pinckney's Treaty in 1795.

European Exploration

On May 8, 1541, Spanish explorer Hernando de Soto became the first recorded European to reach the Mississippi River, which he called Río del Espíritu Santo ("River of the Holy Spirit"), in the area of what is now Mississippi. In Spanish, the river is called Río Mississippi.

French explorers, Louis Jolliet and Jacques Marquette, began exploring the Mississippi in the 17th century. Marquette traveled with a Sioux who named it Ne Tongo ("Big river" in Sioux language) in 1673. Marquette proposed calling it the River of the Immaculate Conception.

In 1682, René-Robert Cavelier, Sieur de La Salle and Henri de Tonti claimed the entire Mississippi River Valley for France, calling the river Colbert River after Jean-Baptiste Colbert and the region La Louisiane, for King Louis XIV. On March 2, 1699, Pierre Le Moyne d'Iberville rediscovered the mouth of the Mississippi, following the death of La Salle. The French built the small fort of La Balise there to control passage.

In 1718, about 100 miles (160 km) upriver, New Orleans was established along the river crescent by Jean-Baptiste Le Moyne, Sieur de Bienville, with construction patterned after the 1711 resettlement on Mobile Bay of Mobile, the capital of French Louisiana at the time.

Native Americans

The area of the Mississippi River basin was first settled by hunting and gathering Native American peoples and is considered one the few independent centers of plant domestication in human history. Evidence of early cultivation of sunflower, a goosefoot, a marsh elder and an indigenous squash dates to the 4th millennium BCE. The lifestyle gradually became more settled after around 1000 BCE during what is now called the Woodland period, with increasing evidence of shelter construction, pottery, weaving and other practices. A network of trade routes referred to as the Hopewell interaction sphere was active along the waterways between about 200 and 500 CE, spreading common cultural practices over the entire area between the Gulf of Mexico and the Great Lakes. A period of more isolated communities followed, and agriculture introduced from Mesoamerica based on the Three Sisters (maize, beans and squash) gradually came to dominate. After around 800 CE there arose an advanced agricultural society today referred to as the Mississippian culture, with evidence of highly stratified complex chiefdoms and large population centers. The most prominent of these, now called Cahokia, was occupied between about 600 and 1400 CE and at its peak numbered between 8,000 and 40,000 inhabitants, larger than London, England of that time. At the time of first contact with Europeans, Cahokia and many other Mississippian cities had dispersed, and archaeological finds attest to increased social stress.

Modern American Indian nations inhabiting the Mississippi basin include Cheyenne, Sioux, Ojibwe, Potawatomi, Ho-Chunk, Fox, Kickapoo, Tamaroa, Moingwena, Quapaw and Chickasaw. The word Mississippi itself comes from Messipi, the French rendering of the Anishinaabe (Ojibwe or Algonquin) name for the river, Misi-ziibi (Great River). The Ojibwe called Lake Itasca Omashkoozo-zaaga'igan (Elk Lake) and the river flowing out of it Omashkoozo-ziibi (Elk River). After flowing into Lake Bemidji, the Ojibwe called the river Bemijigamaag-ziibi (River from the Traversing Lake). After flowing into Cass Lake, the name of the river changes to Gaa-miskwaawaakokaag-ziibi (Red Cedar River) and then out of Lake Winnibigoshish as Wiinibiigoozhish-ziibi (Miserable Wretched Dirty Water River), Gichi-ziibi (Big River) after the confluence with the Leech Lake River, then finally as Misi-ziibi (Great River) after the confluence with the Crow Wing River. After the expeditions by Giacomo Beltrami and Henry Schoolcraft, the longest stream above the juncture of the Crow Wing River and Gichi-ziibi was named "Mississippi River". The Mississippi River Band of Chippewa Indians, known as the Gichi-ziibiwininiwag, are named after the stretch of the Mississippi River known as the Gichi-ziibi. The Cheyenne, one of the earliest inhabitants of the upper Mississippi River, called it the Máʼxe-éʼometaaʼe (Big Greasy River) in the Cheyenne language.

The Bridge Crossings The Mississippi River

The first bridge across the Mississippi River was built in 1855. It spanned the river in Minneapolis, Minnesota where the current Hennepin Avenue Bridge is located.

The first railroad bridge across the Mississippi was built in 1856. It spanned the river between the Rock Island Arsenal in Illinois and Davenport, Iowa. Steamboat captains of the day, fearful of competition from the railroads, considered the new bridge "a hazard to navigation". Two weeks after the bridge opened, the steamboat Effie Afton rammed part of the bridge, catching it on fire. Legal proceedings ensued, with Abraham Lincoln defending the railroad. The lawsuit went to the Supreme Court of the United States and was eventually ruled in favor of the railroad.

Below is a general overview of selected Mississippi bridges which have notable engineering or landmark significance, with their cities or locations. They are sequenced from the Upper Mississippi's source to the Lower Mississippi's mouth.

• Stone Arch Bridge – Former Great Northern Railway (now pedestrian) bridge at Saint Anthony Falls in downtown Minneapolis.

• I-35W Saint Anthony Falls Bridge – In Minneapolis, opened in September 2008, replacing the I-35W Mississippi River bridge which had collapsed catastrophically on August 1, 2007, killing 13 and injuring over 100.
• I-90 Mississippi River Bridge – Connects La Crosse, Wisconsin, and Winona County, Minnesota, located just south of Lock and Dam No. 7.
• Black Hawk Bridge – Connects Lansing in Allamakee County, Iowa and rural Crawford County, Wisconsin; locally referred to as the Lansing Bridge and documented in the Historic American Engineering Record.  

• Julien Dubuque Bridge – Joins the cities of Dubuque, Iowa, and East Dubuque, Illinois; listed in the National Register of Historic Places.

• Savanna-Sabula Bridge – A truss bridge and causeway connecting the city of Savanna, Illinois, and the island city of Sabula, Iowa. The bridge carries U.S. Highway 52 over the river, and is the terminus of both Iowa Highway 64 and Illinois Route 64. Added to the National Register of Historic Places in 1999.
• Fred Schwengel Memorial Bridge – A 4-lane steel girder bridge that connects LeClaire, Iowa, and Rapids City, Illinois. Completed in 1966.
• I-74 Bridge – Originally known as the Iowa-Illinois Memorial Bridge, connecting Bettendorf, Iowa, and Moline, Illinois.
• Government Bridge – Connects Rock Island, Illinois and Davenport, Iowa, adjacent to Lock and Dam No. 15; the fourth crossing in this vicinity, built in 1896.
• Rock Island Centennial Bridge – Connects Rock Island, Illinois, and Davenport, Iowa; opened in 1940.

• Norbert F. Beckey Bridge – Connects Muscatine, Iowa, and Rock Island County, Illinois; became first U.S. bridge to be illuminated with light-emitting diode (LED) lights decoratively illuminating the facade of the bridge.

• Great River Bridge – A cable-stayed bridge connecting Burlington, Iowa, to Gulf Port, Illinois.
• Fort Madison Toll Bridge – Connects Fort Madison, Iowa, and unincorporated Niota, Illinois; also known as the Santa Fe Swing Span Bridge; at the time of its construction the longest and heaviest electrified swing span on the Mississippi River. Listed in the National Register of Historic Places since 1999.
• Bayview Bridge – A cable-stayed bridge bringing westbound U.S. Highway 24 over the river, connecting the cities of West Quincy, Missouri, and Quincy, Illinois. Eastbound U.S. 24 is served by the older Quincy Memorial Bridge.
• Clark Bridge – A cable-stayed bridge connecting West Alton, Missouri, and Alton, Illinois, also known as the Super Bridge as the result of an appearance on the PBS program, Nova; built in 1994, carrying U.S. Route 67 across the river. This is the northernmost river crossing in the St. Louis metropolitan area, replacing the Old Clark Bridge, a truss bridge built in 1928, named after explorer William Clark.

• Chain of Rocks Bridge – Located on the northern edge of St. Louis, notable for a 22-degree bend occurring at the middle of the crossing, necessary for navigation on the river; formerly used by U.S. Route 66 to cross the Mississippi.

• Eads Bridge – A combined road and railway bridge, connecting St. Louis and East St. Louis, Illinois. When completed in 1874, it was the longest arch bridge in the world, with an overall length of 6,442 ft (1,964 m). The three ribbed steel arch spans were considered daring, as was the use of steel as a primary structural material; it was the first such use of true steel in a major bridge project.
• Chester Bridge – A truss bridge connecting Route 51 in Missouri with Illinois Route 150, between Perryville, Missouri, and Chester, Illinois. The bridge can be seen in the beginning of the 1967 film In the Heat of the Night. In the 1940s, the main span was destroyed by a tornado.

• Hernando de Soto Bridge – A through arch bridge carrying Interstate 40 across the Mississippi between West Memphis, Arkansas, and Memphis, Tennessee.

• Frisco Bridge – A cantilevered through truss bridge, carrying a rail line across the river between West Memphis, Arkansas, and Memphis, Tennessee, previously known as the Memphis Bridge. When it opened on May 12, 1892, it was the first crossing of the Lower Mississippi and the longest span in the U.S. Listed as a Historic Civil Engineering Landmark.
• Memphis & Arkansas Bridge – A cantilevered through truss bridge bridge, carrying Interstate 55 between Memphis and West Memphis; listed on the National Register of Historic Places.
• Huey P. Long Bridge – In Jefferson Parish, Louisiana, the first Mississippi River span built in Louisiana.
• Crescent City Connection – Connects the east and west banks of New Orleans, Louisiana; the 5th-longest cantilever bridge in the world.

The John James Audubon Bridge between Pointe Coupee Parish and West Feliciana Parish in Louisiana is under construction; when finished, it will be the longest bridge crossing the Mississippi River.

Communities Along The Mississippi River

Many of the communities along the Mississippi River are listed below. They have either historic significance or cultural lore connecting them to the river. They are ordered from the beginning of the river to its end.

Bemidji, Minnesota Grand Rapids, Minnesota Jacobson, Minnesota Palisade, Minnesota Aitkin, Minnesota Riverton, Minnesota Brainerd, Minnesota Fort Ripley, Minnesota Little Falls, Minnesota Sartell, Minnesota St. Cloud, Minnesota Coon Rapids, Minnesota Monticello, Minnesota Minneapolis, Minnesota Saint Paul, Minnesota Nininger, Minnesota Hastings, Minnesota Prescott, Wisconsin Prairie Island, Minnesota Diamond Bluff, Wisconsin Red Wing, Minnesota Hager City, Wisconsin Maiden Rock, Wisconsin Stockholm, Wisconsin Lake City, Minnesota Maple Springs, Minnesota Camp Lacupolis, Minnesota Pepin, Wisconsin Reads Landing, Minnesota Wabasha, Minnesota Nelson, Wisconsin Alma, Wisconsin Buffalo City, Wisconsin Weaver, Minnesota Minneiska, Minnesota Fountain City, Wisconsin Winona, Minnesota Homer, Minnesota

Trempealeau, Wisconsin Dakota, Minnesota Dresbach, Minnesota La Crescent, Minnesota La Crosse, Wisconsin Brownsville, Minnesota Stoddard, Wisconsin Genoa, Wisconsin Victory, Wisconsin Potosi, Wisconsin De Soto, Wisconsin Preston, Iowa Lansing, Iowa Ferryville, Wisconsin Lynxville, Wisconsin Prairie du Chien, Wisconsin Marquette, Iowa McGregor, Iowa Wyalusing, Wisconsin Guttenberg, Iowa Cassville, Wisconsin Dubuque, Iowa Galena, Illinois Bellevue, Iowa Savanna, Illinois Sabula, Iowa Fulton, Illinois Clinton, Iowa Cordova, Illinois LeClaire, Iowa Bettendorf, Iowa East Moline, Illinois Moline, Illinois Davenport, Iowa Rock Island, Illinois Buffalo, Iowa Muscatine, Iowa New Boston, Illinois Keithsburg, Illinois Oquawka, Illinois Burlington, Iowa Dallas City, Illinois Fort Madison, Iowa Nauvoo, Illinois Keokuk, Iowa

Warsaw, Illinois Quincy, Illinois Hannibal, Missouri Louisiana, Missouri Clarksville, Missouri Portage Des Sioux, Missouri Alton, Illinois St. Louis, Missouri Ste. Genevieve, Missouri Kaskaskia, Illinois Chester, Illinois Grand Tower, Illinois Cape Girardeau, Missouri Thebes, Illinois Commerce, Missouri Cairo, Illinois Wickliffe, Kentucky Columbus, Kentucky Hickman, Kentucky New Madrid, Missouri Tiptonville, Tennessee Caruthersville, Missouri Osceola, Arkansas Reverie, Tennessee Memphis, Tennessee West Memphis, Arkansas Tunica, Mississippi Helena-West Helena, Arkansas Napoleon, Arkansas (historical) Arkansas City, Arkansas Greenville, Mississippi Vicksburg, Mississippi Waterproof, Louisiana Natchez, Mississippi Morganza, Louisiana St. Francisville, Louisiana New Roads, Louisiana Baton Rouge, Louisiana Donaldsonville, Louisiana Lutcher, Louisiana New Orleans, Louisiana Pilottown, Louisiana La Balize, Louisiana (historical)

State Boundaries of The Mississippi River

The Mississippi River runs through or along 10 states, from Minnesota to Louisiana, and was used to define portions of these states' borders, with Wisconsin, Illinois, Kentucky, Tennessee, and Mississippi along the east side of the river, and Iowa, Missouri, and Arkansas along its west side. Substantial parts of both Minnesota and Louisiana are on either side of the river, although the Mississippi defines part of the boundary of each of these states.

In all of these cases, the middle of the riverbed at the time the borders were established was used as the line to define the borders between adjacent states. In various areas, the river has since shifted, but the state borders have not changed, still following the former bed of the Mississippi River as of their establishment, leaving several small isolated areas of one state across the new river channel, contiguous with the adjacent state. Also, due to a meander in the river, a small part of western Kentucky is contiguous with Tennessee, but isolated from the rest of its state.

Longest Continuous Waterway of The Mississippi River

In addition to historical traditions shown by names, there are at least two other measures of a river's identity, one being the largest branch (by water volume), and the other being the longest branch. Using the largest-branch criterion, the Ohio would be the main branch of the Lower Mississippi, not the Middle and Upper Mississippi. Using the longest-branch criterion, the Middle Mississippi-Missouri-Jefferson-Beaverhead-Red Rock-Hellroaring Creek River would be the main branch. In either of these cases, the Upper Mississippi from St. Louis, Missouri, to Minnesota, despite its name, would not be part of the more significant branch.

While the Missouri River, flowing from the confluence of the Jefferson, Madison and Gallatin Rivers to the Mississippi, is the longest continuously named "river" in the United States, the serial combination of Hellroaring Creek and the Red Rock, Beaverhead, Jefferson, Missouri, Middle Mississippi, and Lower Mississippi rivers, considered as one continuous waterway, is the longest river in North America and the third or fourth longest river in the world. Its length of at least 3,745 mi (6,027 km) is exceeded only by the Nile, the Amazon, and perhaps the Yangtze River among the longest rivers in the world. The source of this waterway is at Brower's Spring, 8,800 feet (2,700 m) above sea level in southwestern Montana, along the Continental Divide outside Yellowstone National Park.

The unifying name "Great American River" has been suggested for this multiply named waterway. However, the names "Mississippi River" for the water course from Minnesota to the Gulf of Mexico, "Missouri River" for its major western tributary, and "Ohio River" for its major eastern tributary are so well established that neither reassignment of names nor creation of novel names can be seriously considered as replacements for current usage. Furthermore, the north-south course of the waterway commonly known as the Mississippi River is widely considered a convenient if approximate dividing line between the Eastern, Southern, and Midwestern United States and the Western U.S., as exemplified by the Gateway Arch in St. Louis and the phrase "Trans-Mississippi", used for example in the name of the 1898 Trans-Mississippi Exposition held in Omaha, Nebraska.

Course Changes of The Mississippi River

Ice sheets during the Illinoian Stage about 300,000 to 132,000 years before present, blocked the Mississippi near Rock Island, Illinois, diverting it to its present channel farther to the west, the current western border of Illinois.

The Hennepin Canal roughly follows the ancient channel of the Mississippi downstream from Rock Island to Hennepin. South of Hennepin, Illinois, the current Illinois River is actually following the ancient channel of the Mississippi River to Alton, Illinois, before the Illinoian Stage.

In March 1876, the Mississippi suddenly changed course near the settlement of Reverie, Tennessee, leaving a small part of Tipton County, Tennessee, attached to Arkansas and separated from the rest of Tennessee by the new river channel. Since this event was an avulsion, rather than the effect of incremental erosion and deposition, the state line remains located in the old channel.

Through a natural process known as delta switching, the lower Mississippi River has shifted its final course to the mouth of the Gulf of Mexico every thousand years or so. This occurs because the deposits of silt and sediment begin to clog its channel, raising the river's level and causing it to eventually find a steeper, more direct route to the Gulf of Mexico. The abandoned distributaries diminish in volume and form what are known as bayous. This process has, over the past 5,000 years, caused the coastline of south Louisiana to advance toward the Gulf from 15 to 50 miles (25–80 km). The currently active delta lobe is called the Birdfoot Delta, after its shape, or the Balize Delta, after La Balize, Louisiana, the first French settlement at the mouth of the Mississippi.

Sediment of The Mississippi River

Prior to 1900, the Mississippi River transported an estimated 400 million metric tons of sediment per year from the interior of the United States to coastal Louisiana and the Gulf of Mexico. During the last two decades, this number was only 145 million metric tons per year. The reduction in sediment transported down the Mississippi River is the result of engineering modification of the Mississippi, Missouri, and Ohio rivers and their tributaries by dams, meander cutoffs, river-training structures, and bank revetments and soil erosion control programs in the areas drained by them.

Discharge of The Mississippi River

The Mississippi river discharges at an annual average rate of between 200 and 700 thousand cubic feet per second (7,000–20,000 m³/s). Although it is the 5th largest river in the world by volume, this flow is a mere fraction of the output of the Amazon, which moves nearly 7 million cubic feet per second (200,000 m³/s) during wet seasons. On average, the Mississippi has only 9% the flow of the Amazon River.

Outflow of The Mississippi River

Fresh river water flowing from the Mississippi into the Gulf of Mexico does not mix into the salt water immediately. The images from NASA's MODIS to the right show a large plume of fresh water, which appears as a dark ribbon against the lighter-blue surrounding waters.

The images demonstrate that the plume did not mix with the surrounding sea water immediately. Instead, it stayed intact as it flowed through the Gulf of Mexico, into the Straits of Florida, and entered the Gulf Stream. The Mississippi River water rounded the tip of Florida and traveled up the southeast coast to the latitude of Georgia before finally mixing in so thoroughly with the ocean that it could no longer be detected by MODIS.

Drainage Area and Basin of The Mississippi Rriver

The Mississippi River drains the majority of the area between the Rocky Mountains and the Appalachian Mountains, except for the areas drained to the Hudson Bay via the Red River of the North, by the Saint Lawrence River and the Great Lakes, the Rio Grande (and numerous other rivers in Texas), the Alabama River-Tombigbee River, and the Chattahoochee River-Apalachicola River.

The Mississippi River empties into the Gulf of Mexico about 100 miles (160 km) downstream from New Orleans. Measurements of the length of the Mississippi from Lake Itasca to the Gulf of Mexico vary somewhat, but the United States Geological Survey's number is 2,340 miles (3,770 km). The retention time from Lake Itasca to the Gulf is about 90 days.

Watershed of The Mississippi River

The Mississippi River has the fourth largest drainage basin or "catchment" in the world. The basin covers more than 1,245,000 sq mi (3,220,000 km²), including all or parts of 31 states and two Canadian provinces. The drainage basin empties into the Gulf of Mexico. The total catchment of the Mississippi River covers nearly 40% of the landmass of the continental United States.

Lower Mississippi River

The Mississippi River is called the Lower Mississippi River from its confluence with the Ohio River to its mouth at the Gulf of Mexico.

Measured by water volume, the Lower Mississippi's primary branch is the Ohio River. At the confluence of the Ohio and the Middle Mississippi, the Ohio is the bigger river, with its long-term mean discharge at Cairo, Illinois being 281,500 cu ft/s (7,970 m³/s), while the long-term mean discharge of the Mississippi at Thebes, Illinois (just upriver from Cairo) is 208,200 cu ft/s (5,900 m³/s). Thus, by volume, the main branch of the Mississippi River system at Cairo can be considered to be the Ohio River (and the Allegheny River further upstream), 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; the Yazoo River, meeting the Mississippi at Vicksburg, Mississippi; and the Red River in Louisiana.

The widest point of the Mississippi River is in the Lower Mississippi portion where it exceeds 1 mile (1.6 km) in width in several places.

Due to deliberate water diversion at the Old River Control Structure in Louisiana, the Atchafalaya River in Louisiana is now a major distributary of the Mississippi River, with 30% of the Mississippi's flow routinely entering 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.

Middle Mississippi River

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 190 miles (310 km) to its confluence with the Ohio River at Cairo, Illinois.

The Middle Mississippi is a relatively free-flowing river. From St. Louis to the Ohio River confluence, the Middle Mississippi falls a total of 220 feet (67 m) over a distance of 180 miles (290 km) for an average rate of 1.2 feet per mile (23 cm/km). At its confluence with the Ohio River, the Middle Mississippi is 315 feet (96 m) above sea level. Apart from the Missouri River, no major tributaries enter the Middle Mississippi River.

Measured by length, the Middle Mississippi's primary branch is the Missouri River, not the Upper Mississippi, whether or not additional tributaries upstream are considered. Thus, by length, the main branch of the Mississippi River system at St. Louis can be considered to be the Missouri River, rather than the Upper Mississippi. By taking the longer branch at each significant fork, this continuous but multiply named waterway can be identified and measured. One name for it is the Lower & Middle Mississippi-Missouri-Jefferson-Beaverhead-Red Rock-Hellroaring Creek River. The name "Great American River" has also been suggested for this longest American waterway.

Upper Mississippi River

The Mississippi River is known as the Upper Mississippi from its headwaters to its confluence with the Missouri River at St. Louis, Missouri. The Upper Mississippi is divided into two sections:

1. The headwaters, 493 miles (793 km), from the source to Saint Anthony Falls in Minneapolis, Minnesota
2. A navigable channel, formed by a series of man-made lakes between Minneapolis and St. Louis, Missouri, 664 miles (1,069 km)

The source of the Upper Mississippi branch is traditionally accepted as Lake Itasca, 1,475 feet (450 m) above sea level in Itasca State Park in Clearwater County, Minnesota. The name "Itasca" is a combination of the last four letters of the Latin word for truth (veritas) and the first two letters of the Latin word for head (caput). However, the lake is in turn fed by a number of smaller streams, of which one might be selected as the river's ultimate source.

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 permit 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 Coon Rapids Dam in Coon Rapids, Minnesota. Before its construction in 1913, steamboats could occasionally go upstream as far as Saint Cloud, 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 799 feet (244 m). Below the dam, the river's elevation is 750 feet (230 m). This 49-foot (15 m) 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.

The Upper Mississippi features various natural and artificial lakes, with its widest point being Lake Winnibigoshish, near Grand Rapids, Minnesota, over 7 miles (11 km) across. Also of note is Lake Onalaska, near La Crosse, Wisconsin, over 4 miles (6.4 km) wide. On the other hand, Lake Pepin is natural, formed due to the delta formed by the Chippewa River of Wisconsin as it enters the Upper Mississippi; it is more than 2 miles (3.2 km) wide.

By the time the Upper Mississippi reaches Saint Paul, Minnesota, below Lock and Dam #1, it has dropped more than half its original elevation and is 687 feet (209 m) 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 Black River (Mississippi River), La Crosse River, and Root River (Minnesota) in La Crosse, Wisconsin; the Wisconsin River in Prairie du Chien, Wisconsin; the Rock River in the Quad Cities; the Iowa River near Wapello, Iowa; the Skunk River south of Burlington, Iowa; and the Des Moines River in 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 Big Muddy River, Illinois River, and the Kaskaskia River in Illinois.