The Mississippi River at Columbus Kentucky. Old Man River is economic and ecological powerhouse
Introduction to the River
The Mississippi River is one of the world's major river systems in size, habitat diversity and biological productivity. It is also one of the world's most important commercial waterways and one of North America's great migration routes for both birds and fishes.
Today, the Mississippi River powers a significant segment of the economy in the upper Midwest. Barges and their tows move approximately 175 million tons of freight each year on the upper Mississippi through a system of 29 locks and dams. It is also a major recreational resource for boaters, canoeists, hunters, anglers, and birdwatchers and offers many outdoor opportunities.
The Mississippi River is the second longest river in North America, flowing 2,350 miles from its source at Lake Itasca through the center of the continental United States to the Gulf of Mexico. The Missouri River, a tributary of the Mississippi River, is about 100 miles longer. Some describe the Mississippi River as being the third longest river system in the world, if the length of Missouri and Ohio Rivers are added to the Mississippi's main stem.
When compared to other world rivers, the Mississippi-Missouri River combination ranks fourth in length (3,710 miles/5,970km) following the Nile (4,160 miles/6,693km), the Amazon (4,000 miles/6,436km), and the Yangtze Rivers (3,964 miles/6,378km). At a river's delta, the reported length may increase or decrease as deposition and erosion occurs.
At Lake Itasca, the river is between 20 and 30 feet wide, the narrowest stretch for its entire length. The widest part of the Mississippi can be found at Lake Winnibigoshish near Bena, MN, where it is wider than 11 miles. The widest navigable section in the shipping channel of the Mississippi is Lake Pepin, where the channel is approximately 2 miles wide.
At the headwaters of the Mississippi, the average surface speed of the water is about 1.2 miles per hour - roughly one-half as fast as people walk. At New Orleans the river flows at about three miles per hour. But the speed changes as water levels rise or fall and where the river widens, narrows, becomes more shallow or some combination of these factors. It takes about three months for water that leaves Lake Itasca, the river's source, to reach the Gulf of Mexico.
Another way to measure the size of a river is by the amount of water it discharges. Using this measure the Mississippi River is the 15th largest river in the world discharging 16,792 cubic meters (593,003 cubic feet) of water per second into the Gulf of Mexico. The biggest river by discharge volume is the Amazon at an impressive 209,000 cubic meters (7,380,765 cubic feet) per second. The Amazon drains a rain forest while the Mississippi drains much of the area between the Appalachian and Rocky Mountains, much of which is fairly dry.
At Lake Itasca, the average flow rate is 6 cubic feet per second. At Upper St. Anthony Falls in Minneapolis, the northern most Lock and Dam, the average flow rate is 12,000 cubic feet per second or 89,869 gallons per second. At New Orleans, the average flow rate is 600,000 cubic feet per second.
Some like to measure the size of a river is by the size of its watershed, which is the area drained by a river and its tributaries. The Mississippi River drains an area of about 3.2 million square kilometers (1.2 million square miles) including all or parts of 32 states and two Canadian provinces, about 40% of the continental United States. The Mississippi River watershed is the fourth largest in the world, extending from the Allegheny Mountains in the east to the Rocky Mountains in the west. The Amazon for comparison drains about 7.1 million square kilometers (2.7 million square miles).
Communities up and down the river use the Mississippi to obtain freshwater and to discharge their industrial and municipal waste. We don't have good figures on water use for the whole Mississippi River Basin, but we have some clues. A January 2000 study published by the Upper Mississippi River Conservation Committee states that close to 15 million people rely on the Mississippi River or its tributaries in just the upper half of the basin (from Cairo, IL to Minneapolis, MN). A frequently cited figure of 18 million people using the Mississippi River Watershed for water supply comes from a 1982 study by the Upper Mississippi River Basin Committee. The Environmental Protection Agency simply says that more than 50 cities rely on the Mississippi for daily water supply.
Agriculture has been the dominant land use for nearly 200 years in the Mississippi basin, and has altered the hydrologic cycle and energy budget of the region. The agricultural products and the huge agribusiness industry that has developed in the basin produce 92% of the nation's agricultural exports, 78% of the world's exports in feed grains and soybeans, and most of the livestock and hogs produced nationally. Sixty percent of all grain exported from the US is shipped on the Mississippi River through the Port of New Orleans and the Port of South Louisiana.
In measure of tonnage, the largest port district in the world is located along the Mississippi River delta in Louisiana. The Port of South Louisiana is one of the largest volume ports in the United States. Representing 500 million tons of shipped goods per year (according to the Port of New Orleans), the Mississippi River barge port system is significant to national trade.
Shipping at the lower end of the Mississippi is focused on petroleum and petroleum products, iron and steel, grain, rubber, paper, wood, coffee, coal, chemicals, and edible oils.
To move goods up and down the Mississippi, the U.S. Army Corps of Engineers maintains a 9-foot shipping channel from Baton Rouge, LA to Minneapolis, MN. From Baton Rouge past New Orleans to Head of Passes, a 45-foot channel is maintained to allow ocean-going vessels access to ports between New Orleans and Baton Rouge.