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Mississippi River
Misi-ziibi (Ojibwe)
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| Length | 2,350 miles (3,782 km)[1] | ||||||||||||||||
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| Source | Lake Itasca, Clearwater County, Minnesota[2] | ||||||||||||||||
| Mouth | Gulf of Mexico, below New Orleans, Louisiana[1] | ||||||||||||||||
| Drainage basin | 1.2 million square miles (3.2 million km²)[1] | ||||||||||||||||
| States on the main stem | Minnesota · Wisconsin · Iowa · Illinois · Missouri · Kentucky · Tennessee · Arkansas · Mississippi · Louisiana | ||||||||||||||||
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The Mississippi River is the principal river of the United States and the second longest in North America, after its own tributary the Missouri River. It runs about 2,350 miles from Lake Itasca in northern Minnesota to the Gulf of Mexico below New Orleans, though published lengths vary because the channel shifts and different agencies measure it differently.[1] Its watershed covers roughly 1.2 million square miles and takes in all or part of 31 states and two Canadian provinces — about 40% of the contiguous United States.[1]
The river is one of the busiest commercial waterways in the world and one of the continent's great migration routes for birds and fish.[1] Barge tows carry roughly 175 million tons of freight a year on the upper river alone, and the basin produces most of the country's agricultural exports.[1] Control of the Mississippi shaped early American expansion, and a century of federal engineering has since turned much of it into a managed channel held in place by levees, locks and revetments.[4]
The English name comes through French from an Anishinaabe (Ojibwe) word, usually given as misi-ziibi and translated as "great river" or "gathering of waters".[5] Ojibwe speakers did not use one name for the whole waterway; different stretches carried different names, and the lake at its head was known as Elk Lake.[2]
The name Itasca is much newer and entirely invented. Henry Rowe Schoolcraft reached the source in 1832 with the Ojibwe guide Ozawindib and coined it from the Latin phrase veritas caput, meaning "true head".[2]
The river leaves Lake Itasca as a stream 20 to 30 feet wide and roughly knee deep, then wanders north and east through the lakes and bogs of northern Minnesota before turning south.[1][2] It covers 694 miles inside Minnesota alone.[2] At Saint Anthony Falls in Minneapolis it becomes navigable, and from there to the mouth of the Ohio River at Cairo, Illinois, it is known as the Upper Mississippi.[3]
This reach is a stepped waterway rather than a free-flowing one. Twenty-nine locks and dams between Minneapolis and St. Louis hold the water in a chain of pools, and vessels are raised or lowered between them like steps on a staircase.[3] The widest point on the whole river lies in this stretch, at Lake Winnibigoshish in Minnesota, where it spreads beyond 11 miles.[1]
Below Cairo the river doubles in volume as the Ohio joins it, and the character of the valley changes completely. There are no dams on the Lower Mississippi; the channel is instead held in place by levees, dredging and bank protection.[4] The Arkansas, Red and Yazoo rivers enter along the way, and the river swings past Memphis, Vicksburg and Baton Rouge on a floodplain of its own making.
Between 1932 and 1946 engineers cut fifteen artificial bends out of the channel, shortening the river by roughly a quarter between Memphis and Baton Rouge and lowering flood heights at several gauges.[4] Its deepest point, near Algiers Point in New Orleans, is about 200 feet.[1]
South of New Orleans the river breaks into distributaries[note 1] and spreads sediment across a delta that has been built and rebuilt many times. Most of that sediment is now trapped behind upstream dams and inside the leveed channel, so the delta is eroding rather than growing.[4]
A drop of water leaving Lake Itasca takes about three months to reach the sea.[1] United States federal agencies have called the receiving body of water the Gulf of America since February 2025, under Executive Order 14172; Gulf of Mexico remains the name in general international use.[6]
Indigenous nations lived along the river for thousands of years and used it for food, travel and trade long before any European saw it.[1] The first documented European sighting came in 1541, when the Spanish expedition of Hernando de Soto reached the lower river; the Spanish were looking for gold and made little of the find.[7]
French interest was more sustained. In 1673 Louis Jolliet and the Jesuit missionary Jacques Marquette paddled from the Great Lakes down to the mouth of the Arkansas River, establishing that the river ran toward the Gulf rather than the Pacific.[8] Nine years later René-Robert Cavelier, Sieur de La Salle, followed it to the sea and claimed the river and its whole basin for France.[8]
For American settlers pushing into the Ohio and Tennessee valleys, the Mississippi was the only practical route to market, and New Orleans was the gate at the end of it. A Spanish decision to withdraw American storage rights at the port in 1802 turned that dependence into a crisis.[9]
Thomas Jefferson sent envoys to buy New Orleans; Napoleon, short of money and losing interest in a North American empire, offered the whole territory instead. The treaty signed on 30 April 1803 transferred 828,000 square miles west of the river for $15 million and roughly doubled the size of the United States.[10]
The first steamboat on the Mississippi, the New Orleans, made its voyage in December 1811, and within a generation the trade had transformed the valley: some 230 steamboats worked the river by 1834.[11] Settlement followed the boats, and Native nations were dispossessed as farms and cities replaced them along the banks.[1]
Federal control arrived in stages. Congress created the Mississippi River Commission in 1879 to improve the river's condition, promote navigation and prevent destructive floods.[12] In 1930 it authorized a navigation channel at least 9 feet deep and 400 feet wide on the upper river, and the lock-and-dam system was built through the following decade.[3][13] Diesel towboats pushing barges had replaced the last steamboats by 1930.[11]
The Great Mississippi Flood of 1927 remains the most destructive river flood in United States history. Heavy rain from August 1926 through the following spring overwhelmed levees built and maintained by local boards, and the river reached about 80 miles wide near Vicksburg.[14] Official figures record 246 deaths, more than 700,000 people made homeless and 27,000 square miles under water, with damage above $400 million in the money of the day.[14] The burden fell hardest on Black sharecroppers in the Delta, many of whom were held in guarded camps and later joined the migration north.[14]
Congress responded with the Flood Control Act of 1928, which made flood control on the Mississippi a federal responsibility and authorized the Mississippi River and Tributaries Project.[14] That project rests on four elements: levees to contain flood flows, floodways to carry excess water past vulnerable reaches, channel work to stabilize the bed and banks, and improvements on the tributaries.[4] Its levee system runs to some 3,787 miles of authorized embankments and floodwalls, of which about 2,216 miles line the main stem.[15]
Three relief valves sit along the lower river. The Birds Point–New Madrid floodway below Cairo takes water through deliberately weakened levee sections at extreme stages. The Morganza floodway, completed in 1955, can divert up to 600,000 cubic feet per second toward the Atchafalaya basin. Nearer the coast, the Bonnet Carré spillway above New Orleans can send another 250,000 cubic feet per second into Lake Pontchartrain.[4] A separate structure at Old River keeps the Mississippi from abandoning its channel altogether and switching into the shorter, steeper Atchafalaya route to the sea.[4]
The Corps of Engineers maintains a 9-foot channel from Minneapolis down to Baton Rouge and a 45-foot channel below that, deep enough for ocean-going ships to reach the Louisiana ports.[1] Around 500 million tons of cargo move through the barge system each year, and the port district on the lower river is the largest in the world by tonnage.[1] Shipments include grain, coal, petroleum products, chemicals, steel and fertilizer, and about 60% of American grain exports leave through the Louisiana ports.[1]
That dependence makes the river's water level a national economic variable. Drought pushed the Lower Mississippi to record lows in autumn 2022 and again in 2023. The gauge at Memphis read −10.81 feet in October 2022, the lowest since records began there in 1954, and came close to that mark a year later.[16] Low water forces barges to load lighter and travel in smaller tows, which raises freight rates at exactly the point in the year when the corn and soybean harvests need moving.[17] Similar restrictions returned in 2024 and 2025, and the Corps has responded by shifting dredging equipment to the worst shoals.[17]
The Mississippi and its floodplain support a remarkable range of life for a temperate river. At least 260 fish species live in it, a quarter of all the fish species in North America, alongside more than 50 mammal species and at least 145 amphibians and reptiles on the upper river.[1] Mussel diversity is high, with 38 documented species above Cairo and as many as 60 below it.[1]
The corridor matters even more to birds. Some 326 species, or 60% of all North American birds, use the basin as a migratory flyway. Forty percent of the country's migratory waterfowl pass along the river itself each spring and autumn.[1]
Nitrogen and phosphorus washing off farmland and city streets throughout the basin feed algae blooms near the river's mouth. When the algae die and sink, their decay strips oxygen from the bottom water, creating a hypoxic zone[note 2] that kills or drives off marine life each summer.[18]
The 2026 forecast put the zone at roughly 7,027 square miles, well above the 39-year average of 5,223 but below the 2017 record of 8,776.[18] An interagency task force of federal, state and tribal bodies has set a target of 1,900 square miles by 2035 and reports meeting an interim goal of cutting nutrient loads by 20%.[18]
Bighead, silver, black and grass carp escaped from aquaculture ponds into the lower river after flooding in the 1970s and spread through the basin, out-competing native fish and creating hazards for boaters.[19] They have worked as far north as the Illinois River, within reach of the Great Lakes.[19] The Brandon Road Interbasin Project, a set of barriers proposed at a lock and dam near Joliet, Illinois, is intended to stop them crossing over.[20]
The same levees and dams that protect the valley and hold the channel in place also keep sediment from reaching the coast. Silt that once rebuilt the delta each year now settles behind reservoirs or stays inside the leveed channel, and the wetlands at the river's mouth are losing ground to the sea.[4]
No writer is more closely tied to the Mississippi than Mark Twain, who piloted steamboats on it before he wrote about it. Life on the Mississippi (1883) is his account of that work, and the river carries the plot of Adventures of Huckleberry Finn (1884).[21]
The 1927 flood left its own mark on American music. Displaced Delta workers who left for cities such as Chicago carried accounts of the broken levees with them, and those stories fed directly into the blues.[14]
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