The Mississippi River is over 2,300 miles in length. It is the world's second largest drainage basin, measuring over 16,500 miles from its more than 250 tributaries, which encompass 30 US states and 2 Canadian provinces. It has the greatest water carrying capacity of any river on the North American continent, providing the Gulf of Mexico with more than 90% of its fresh water.

The river provides a habitat for 278 fish and mussel species; its bluffs and bottomlands support 45 amphibious and reptile species and over 50 species of mammals; and 40% of the nation's migratory waterfowl depend on the Mississippi corridor for their flyaway. The river sustains over 5 million acres of forested wetlands and provides over 18 million people with their daily water supply.