The Mississippi is one of the world’s great continental rivers, like the Amazon in South America, the Congo in Africa, or the Volga in Europe. Its waters are gathered from two-thirds of the US and, together with the Missouri, which is its chief western branch, the Mississippi flows some 6.400 kilometres from its northern sources in the Rocky Mountains to the Gulf of Mexico, which makes it one of the world’s longest waterways. The Mississippi has been called the “father of waters”. Through all its lower course, it wanders along, appearing lazy and harmless. But people who know the river are not deceived by its benign appearance, for they have had many bitter struggles with its floods. They have had to learn that nothing is to be gained by fighting against the rages of the mighty stream. To control it, Americans have had to accept some of the river’s own terms and to undertake the patient work of conserving and rebuilding soil, grasslands and forests, far back where the waters begin to gather.