The Spanish explorer Hernando De Soto is credited with the European discovery of the Mississippi River in 1541. The French explorers Jacques Marquette and Louis Jolliet reached it through the Wisconsin River in 1673, and in 1682 La Salle traveled down the river to the Gulf of Mexico and claimed the entire territory for France. The French founded New Orleans in 1718 and effectively extended control over the upper river basin with settlements at Cahokia, Kaskaskia, Prairie du Chien, and St. Louis. France ceded the river to Spain in 1763 but regained it in 1800; the United States acquired the Mississippi River as part of the Louisiana Purchase in 1803.
A major artery for the Native Americans and the fur-trading French, the river became in the 19th cent. the principal outlet for the newly settled areas of mid-America; exports were floated downstream with the current, and imports were poled or dragged upstream on rafts and keelboats. The first steamboat plied the river in 1811, and successors became increasingly luxurious as river trade increased in profitability and importance; the era is colorfully described in Mark Twain's Life on the Mississippi (1883).
Traffic from the north ceased after the outbreak of the Civil War. During the Civil War the Mississippi was an invasion route for Union armies and the scene of many important battles. Especially decisive were the capture of New Orleans (1862) by Adm. David Farragut, the Union naval commander, and the victory of Union forces under Grant at Vicksburg in 1863. River traffic resumed after the war, but much of the trade was lost to the railroads. With modern improvements in the channels of the river there has been a great increase in traffic, especially since the mid-1950s, with principal freight items being petroleum products, chemicals, sand, gravel, and limestone.