The Mississippi River is important due to its necessity in American commerce. Cities such as New Orleans, St. Louis and Minneapolis all get water from the river.
The Mississippi River provides hydroelectric power to a number of different cities. The river is the second longest in the United States and has 25 locks and dams. The river also drains off floodwater, which prevents many regions throughout the United States from flooding. In fact, there are 31 states and 2 Canadian provinces that drain water into the Mississippi. This includes thousands of rivers and streams, which make up its system of drainage. Transportation barges throughout the Midwest can ship to and from ports accessible through the Gulf of Mexico, making it important to trade and transportation. Transport along the river is the cheapest form of transportation going back and forth from the Southeast United States. The river was critical in the Civil War, and many boats fought on it for control of the various ports located along the river. The steamboat trade of the Civil War was particularly important, though it was largely replaced by rails.
Hernando de Soto discovered the river for Europeans in 1541, though other cultures, such as the Spanish, had likely already discovered it.