The Mississippi and Missouri Rivers helped shape the economy of the United States. Today, huge barges make their way through elaborate lock and dam systems, requiring no less skill than that of the famous steamboat pilots of old, so strongly evoked by Mark Twain.

Its catchment basin is the size of the Indian subcontinent and, at nearly 2.400 miles, it is the third longest river in the world. Come journey along the Mississippi from its mouth in the salt marshes of the Gulf Coast to its source deep in the northern forests near the Canadian border.