1A major river in North America that rises in Minnesota near the Canadian border and flows south to a delta on the Gulf of Mexico. With its chief tributary, the Missouri River, it is 3,710 miles (5,970 km) long. In the second half of the 17th century it provided a route south through the center of the continent for French explorers from Canada. From the 1830s, it was noted for the sternwheeler steamboats that plied between New Orleans and St. Louis and other northern cities.
2A state of the southern US, on the Gulf of Mexico, bounded to the west by the lower Mississippi River; population 2,938,618 (est. 2008); capital, Jackson. A French colony in the first half of the 18th century, it was ceded to Britain in 1763 and to the US in 1783, becoming the 20th state in 1817.