The Mississippi River Alluvial Plain, the largest ecoregion in Louisiana, covers some 12,350 square miles (31,990 square kilometres) of the state. It occupies parts of seven states, from southern Louisiana to southern Illinois. The northern portion in eastern Arkansas, southeastern Missouri, westernmost Tennessee, westernmost Kentucky and southern Illinois is referred to as the Mississippi embayment. In Louisiana, it includes all of the historic Mississippi River floodplain.

Regions of the United States