Tuesday, August 16, 2011
The Mississippi River
The Mississippi in flood between Missouri and Illinois
The Mississippi River is the largest river system in North America. Flowing entirely in the United States, this river rises in western Minnesota and meanders slowly southwards for 2,320 miles (3,730 km) to the Mississippi River Delta at the Gulf of Mexico. With its many tributaries, the Mississippi's watershed drains all or parts of 31 U.S. states between the Rocky and Appalachian Mountains and even reaches into southern Canada. The Mississippi ranks fourth longest and tenth largest among the world's rivers.
For at least 10,000 years, Native Americans have lived along the Mississippi and its tributaries. Most were hunter-gatherers or herders, but some such as the Mound builders formed prolific agricultural societies. The arrival of Europeans in the 1500s forever changed the native way of life as first explorers, then settlers, ventured into the basin in increasing numbers. The river served first as barrier – forming borders for New Spain, New France, and the early United States – then as vital transportation artery and communications link. In the 19th century, during the height of Manifest Destiny, the Mississippi and several western tributaries, most notably the Missouri, formed pathways for pioneers partaking in the western expansion of the United States.
Formed from thick layers of this river's silt deposits, the Mississippi River Valley is one of the most fertile agricultural regions of the country and as a result came the rise of the river's storied steamboat era. During the American Civil War, the Mississippi's capture by Union forces marked a turning point towards victory because of this very importance as a route of trade and travel, not least to the Confederacy. Because of substantial growth of cities, and the larger ships and barges that have supplanted riverboats, the decades following the 1900s saw massive engineering works applied to the river system, such as the often in-combination construction of levees, locks and dams.
Since modern development of the basin began, the Mississippi has also seen its share of pollution and environmental problems – most notably large volumes of agricultural runoff, which has led to the Gulf of Mexico dead zone off the Delta. In recent years, the river has shown a steady shift towards the Atchafalaya River channel in the Delta; a course change would prove disastrous to seaports such as New Orleans. A system of dikes and gates has so far held the Mississippi at bay, but due to fluvial processes the shift becomes more likely each year.
Name origin: Ojibwe word misi-ziibi, meaning "Great River", or gichi-ziibi, meaning "Big River"
Border States: Minnesota, Wisconsin, Iowa, Illinois, Missouri, Kentucky, Tennessee, Arkansas, Mississippi, Louisiana
Map of the course, watershed, and major tributaries of the Mississippi River
Detailed map of Mississippi River tributary structure
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.
The geographical setting of the Mississippi River includes considerations of the course of the river itself, its watershed, its outflow, its prehistoric and historic course changes, and possibilities of future course changes. The New Madrid Seismic Zone along the river is also noteworthy. These various basic geographical aspects of the river in turn underlie its human history and present uses of the waterway and its adjacent lands.
The Mississippi River is divided into the Upper Mississippi, the Middle Mississippi, and the Lower Mississippi, with the Upper Mississippi upriver of its confluence with the Missouri River, the Middle Mississippi from there downriver to the Ohio River, and the Lower Mississippi from there downriver to the Gulf of Mexico.
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:
The headwaters, 493 miles (793 km), from the source to Saint Anthony Falls in Minneapolis, Minnesota
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.
The beginning of the Mississippi River at Lake Itasca (2004)
Mississippi Head of Navigation: Coon Rapids Dam
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 Coon Rapids Dam in Coon Rapids, Minnesota. Before its construction 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 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 (created by Lock and Dam No. 7), 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.
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 (as at Vicksburg, Mississippi).
The confluence of the Mississippi and Ohio rivers at Cairo, Illinois, the demarcation between the Middle and the Lower Mississippi River.
Middle and Lower 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 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, and the Kaskaskia River in Illinois, 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.
Lower Mississippi River near New Orleans
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 being sent 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.
Mississippi Watershed 2005
The Mississippi River has the world's fourth largest drainage basin ("watershed" or "catchment"). The basin covers more than 1,245,000 sq mi (3,220,000 km2), including all or parts of 32 U.S. states and two Canadian provinces. The drainage basin empties into the Gulf of Mexico, part of the Atlantic Ocean. The total catchment of the Mississippi River covers nearly 40% of the landmass of the continental United States.
In the United States, the Mississippi River drains the majority of the area between crest of the Rocky Mountains and the crest of the Appalachian Mountains, except for various regions drained to Hudson Bay by the Red River of the North; to the Atlantic Ocean by the Great Lakes and the Saint Lawrence River; and to the Gulf of Mexico by the Rio Grande, the Alabama and Tombigbee rivers, the Chattahoochee and Appalachicola rivers, and various smaller coastal waterways along the Gulf.
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.
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. These 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.
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.
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 typically about 90 days.
Over geologic time, the Mississippi River has experienced numerous large and small changes to its main course, as well as additions, deletions, and other changes among its numerous tributaries, and the lower Mississippi River has used different pathways as its main channel to the Gulf of Mexico across the delta region.
Through a natural process known as avulsion or 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.
The current form of the Mississippi River basin was largely shaped by the Laurentide Ice Sheet of the most recent Ice Age. The southernmost extent of this enormous glaciation extended well into the present-day United States and Mississippi basin. When the ice sheet began to recede, hundreds of feet of rich sediment were deposited, creating the flat and fertile landscape of the Mississippi Valley. During the melt, giant glacial rivers found drainage paths into the Mississippi watershed, creating such features as the Minnesota River, James River, and Milk River valleys. When the ice sheet completely retreated, many of these "temporary" rivers found paths to Hudson Bay or the Arctic Ocean, leaving the Mississippi Basin with many features "oversized" for the existing rivers to have carved in the same time period.
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, Illinois. South of Hennepin, to Alton, Illinois, the current Illinois River follows the ancient channel used by the Mississippi River before the Illinoian Stage.
Historic Course Changes
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.
View along the former riverbed at the Tennessee/Arkansas state line near Reverie, Tennessee (2007)
Future Course Changes
Geologists consider the next major change in the course of the Lower Mississippi now overdue. Either of two new routes — through the Atchafalaya Basin or through Lake Pontchartrain — might become the Mississippi's main channel if flood-control structures are overtopped or heavily damaged during a severe flood. Such a course change may not be imminent; the Mississippi returned to its present course following the great floods in 2011.
Failure of the Old River Control Structure, the Morganza Spillway, or nearby levees would likely re-route the main channel of the Mississippi through Louisiana's Atchafalaya Basin and down the Atchafalaya River to reach the Gulf of Mexico south of Morgan City in southern Louisiana. This route provides a more direct path to the Gulf of Mexico than the present Mississippi River channel through Baton Rouge and New Orleans. While the risk of such a diversion is present during any major flood event (such as those of 1973 or 2011), such a change has so far been prevented by active human intervention involving the construction, maintenance, and operation of various levees, spillways, and other control structures by the U.S. Army Corps of Engineers.
The Old River Control Structure complex. View is to the east-southeast, looking downriver on the Mississippi, with the three dams across channels of the Atchafalaya River to the right of the Mississippi. Concordia Parish, Louisiana is in the foreground, on the right, and Wilkinson County, Mississippi, is in the background, across the Mississippi on the left.
New Madrid Seismic Zone
The New Madrid Seismic Zone, along the Mississippi River near New Madrid, Missouri, between Memphis and St. Louis, is related to an aulacogen (failed rift) that formed at the same time as the Gulf of Mexico. This area is still quite active seismically. Four great earthquakes in 1811 and 1812, estimated at approximately 8 on the Richter magnitude scale, had tremendous local effects in the then sparsely settled area, and were felt in many other places in the midwestern and eastern U.S. These earthquakes created Reelfoot Lake in Tennessee from the altered landscape near the river, and temporarily reversed the direction of flow of the Mississippi itself.
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.
The Old River Control Structure, between the present Mississippi River channel and the Atchafalaya Basin, sits at the normal water elevation and is ordinarily used to divert 30% of the Mississippi's flow to the Atchafalaya River. There is a steep drop here away from the Mississippi's main channel into the Atchafalaya Basin. If this facility were to fail during a major flood, there is a strong concern the water would scour and erode the river bottom enough to capture the Mississippi's main channel. The structure was nearly lost during the 1973 flood, but repairs and improvements were made after engineers studied the forces at play. In particular, the Corps of Engineers made many improvements and constructed additional facilities for routing water through the vicinity. These additional facilities give the Corps much more flexibility and potential flow capacity than they had in 1973, which further reduces the risk of a catastrophic failure in this area during other major floods, such as those of 2011.
Because the Morganza Spillway is located at slightly higher elevation well back from the river, it is normally dry on both sides. Even if this structure were to fail at the crest during a severe flood, the flood waters would have to cause a significant amount of erosion, down to normal water levels, before the Mississippi could permanently jump channel at this location. During the 2011 floods, the Corps of Engineers decided to open the Morganza Spillway to 1/4 of its capacity to allow 150,000 ft3/sec of water to flood the Morganza and Atchafalaya floodways and continue directly to the Gulf of Mexico, bypassing Baton Rouge and New Oreans. In addition to reducing the Mississippi River crest downstream, this diversion is also reducing the chances of a channel change by reducing stress on the other elements of the control system.
Some geologists have noted that the possibility for course change ino the Atchafalaya also exists in the area immediately north of the Old River Control Structure. Army Corps of Engineers geologist Fred Smith once stated, "The Mississippi wants to go west. 1973 was a forty-year flood. The big one lies out there somewhere—when the structures can't release all the floodwaters and the levee is going to have to give way. That is when the river's going to jump its banks and try to break through."
If the main channel of the lower Mississippi River changes permanently to the Old River and Atchafalya River channels in the Atchafalaya Basin, thus bypassing Baton Rouge and New Orleans, the ecological and economic consequences for Louisiana, the region, the nation, and international commerce would be immense.
Sedimentation and erosion patterns would quickly change greatly, including development of a new river channel and delta, as well as a new pattern of floodplains, natural levees, and backswamps. Changes to salinity of coastal waters (less saline near new delta, more saline near the present delta) would affect marine life, fisheries, beaches, and coastal marshes. The abandoned river channel would eventually fill and revegetate, probably with a major influx of invasive non-native species. On the other hand, the low-lying outer parts of the present delta, lacking replenishment, would mostly soon erode away. Over time, the new channel would itself develop meanders and cutoffs, eventually leading to formation of new oxbow lakes.
Human society would also be greatly altered locally, with broader consequences nationally and globally. Transportation by road, rail, sea, and river barge would all be dramatically affected, and various sizable new bridges would be urgently needed. Existing port facilities may have to be relocated or replaced, and channel alterations would be needed to maintain any substantial degree of commercial shipping on either the new or the old channel of the Mississippi. Power lines, pipelines, and fiber-optic and other communications lines would be similarly disrupted, and housing, agriculture, forestry, petroleum-production facilities, and other land uses would be suddenly altered, as would patterns of recreational activities. Morgan City in particular would be quite heavily impacted. Values of many properties would be greatly altered, some increasing, some decreasing, and ownership claims would need to be resolved for the newly exposed land of the old riverbed.
Another possible course change for the Mississippi River is a diversion into Lake Pontchartrain near New Orleans, Louisiana. This route is currently controlled by the he Bonnet Carré Spillway, built to reduce flooding in New Orleans. However, the spillway and an imperfect natural levee about 4–6 meters (12 to 20 feet) high are all that prevents the Mississippi from taking a new, shorter course through Lake Pontchartrain to the Gulf of Mexico. Diversion of the Mississippi's main channel through Lake Pontchartrain would have generally similar consequences to an Atchafalaya diversion, but to a lesser extent, since the present river channel would remain in use past Baton Rouge and into the New Orleans area. Following a Lake Pontchartrain diversion, the Mississippi's new delta would develop offshore of southern Mississippi.
The Stone Arch Bridge, the Third Avenue Bridge and the Hennepin Avenue Bridge in Minneapolis (2004)
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. No highway or railroad tunnels cross under the Mississippi River.
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.
The Dubuque-Wisconsin Bridge (2004)
Dubuque-Wisconsin Bridge – Connects Dubuque, Iowa, and Grant County, Wisconsin.
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 – Connects Bettendorf, Iowa, and Moline, Illinois; originally known as the Iowa-Illinois Memorial Bridge.
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 at Muscatine, Iowa, with LED lighting
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.
Quincy Memorial Bridge – Connects the cities of West Quincy, Missouri, and Quincy, Illinois, carrying eastbound U.S. 24, the older of these two U.S. 24 bridges.
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.
The Chain of Rocks Bridge at St.Louis, Missouri
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.
Bill Emerson Memorial Bridge—Connecting Cape Girardeau, Missouri and East Cape Girardeau, Illinois, completed in 2003 and illuminated by 140 lights.
The Hernando de Soto Bridge in Memphis, Tennessee (2009)
Hernando de Soto Bridge – A through arch bridge carrying Interstate 40 across the Mississippi between West Memphis, Arkansas, and Memphis, Tennessee.
Harahan Bridge – A cantilevered through truss bridge, carrying two rail lines of the Union Pacific Railroad across the river 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.
Old Vicksburg Bridge
John James Audubon Bridge – The longest cable-stayed span in the Western Hemisphere; connects Pointe Coupee and West Feliciana Parishes in Louisiana. It is the only crossing between Baton Rouge and Natchez. This bridge was opened a month ahead of schedule in May 2011, due to the 2011 floods.
Huey P. Long Bridge – A truss cantilever bridge carrying US 190 (Airline Highway) and one rail line between East Baton Rouge and West Baton Rouge Parishes in Louisiana.
Horace Wilkinson Bridge – A cantilevered through truss bridge, carrying six lanes of Interstate 10 between Baton Rouge and Port Allen in Louisiana. It is the highest bridge over the Mississippi River.
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 fifth-longest cantilever bridge in the world.
Navigation And Flood Control
Towboat and barges at Memphis, Tennessee
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 1820's, 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 1880's did steamboat traffic diminish. Steamboats remained a feature until the 1920's. 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 1930's, 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.
The Delta Queen at Paducah, Kentucky, 2007.
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 Lower 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.
In Popular Culture
William Faulkner uses the Mississippi River and Delta as the setting for many hunts throughout his novels. It has been proposed that in Faulkner's famous story, The Bear, young Ike first begins his transformation into a man, thus relinquishing his birthright to land in Yoknapatawpha County through his realizations found within the woods surrounding the Mississippi River.
Many of the works of Mark Twain deal with or take place near the Mississippi River. One of his first major works, Life on the Mississippi, is in part a history of the river, in part a memoir of Twain's experiences on the river, and a collection of tales that either take place on or are associated with the river. 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 Twain devoted an entire chapter to him in Life on the Mississippi, and Murrell was rumored to have an island headquarters on the river at Island 37. Twain's most famous work, Adventures of Huckleberry Finn, is largely a journey down the river. The novel works as an episodic meditation on American culture with the river having multiple different meanings including independence, escape, freedom, and adventure.
Herman Melville's novel The Confidence-Man portrayed a Canterbury Tales-style group of steamboat passengers whose interlocking stories are told as they travel down the Mississippi River. The novel is written both as cultural satire and a metaphysical treatise. Like Huckleberry Finn, it uses the Mississippi River as a metaphor for the larger aspects of American and human identity that unify the otherwise disparate characters. The river's fluidity is reflected by the often shifting personalities and identities of Melville's "confidence man".
On The Mississippi, music sheet cover for a 1912 song
The song "When the Levee Breaks", made famous in the version performed by Led Zeppelin on the album Led Zeppelin IV, was composed by Memphis Minnie McCoy in 1929 after the Great Mississippi Flood of 1927. Another song about the flood was "Louisiana 1927" by Randy Newman for the album Good Old Boys.
Ferde Grofé composed a set of movements for symphony orchestra based on the lands the river travels through in his "Mississippi Suite".
The stage and movie musical Show Boat's central musical piece is the spiritual-influenced ballad "Ol' Man River".
The musical Big River is based on the travels of Huckleberry Finn down the river.
The Johnny Cash song "Big River" is about the Mississippi River, and about drifting the length of the river to pursue a relationship that fails.
"Mississippi Queen" by the rock group Mountain makes reference to the river.
"Roll On Mississippi" and "Mississippi Cotton Picking Delta Town" are two classics from Charley Pride that refer to the Mississippi River.
In one of his books, DuBose Heyward claims that jazz got its name from a black itinerant musician called Jazbo Brown. Around the turn of the 19th century the semi-legendary Brown is said to have played on boats along the Mississippi River, as suggested in "Jazzbo Brown from Memphis Town", performed by Bessie Smith.
The late Conway Twitty and Loretta Lynn collaborated on the song "Louisiana Woman, Mississippi Man" about lovers separated by the mighty river, but are not afraid to swim it, even at the risk of alligator bites, at a one-mile (1.6 km) wide juncture separating the two states, for a rendezvous.