The Mississippi River is a large river in the central United States. It is the second longest river in the U.S., after the Missouri River. The Mississippi flows from its source in central Minnesota through the American Midwest into the Gulf of Mexico. It has been a vital transportation artery since the 19th century. It has many tributaries, including the Ohio River, the Arkansas River, the Illinois River, and the Missouri. Notable cities on its banks include St. Louis, Minneapolis, Memphis, and New Orleans.