Mississippi River

Its tributaries spanning montana to New York and its main channel from Minnesota to Louisiana, the Mississippi River is the biggest in North America and the second largest in the Americas behind the Amazon. The river drains much of the interior of North America and shapes the land through sediment erosion and deposition, building an alluvial [Page 1149]landmass from Cairo, Illinois down to the marshes of South Louisiana. At its mouth, where thousands of square miles of land owe their tenuous existence to the whims of the river's choice of outlet, the river builds up and abandons deltaic lobes every few centuries. Every day hundreds of thousands of tons of sediment are moved by the river off the continent and into the Gulf.