St. Louis marks a dividing line in the Mississippi River. To the north, in Minnesota, it is a national treasure attracting more people for recreation than Yellowstone National Park. To the south, it is hardly a river anymore. It more closely resembles a drainage pipe.
As it journeys through the middle of America, the Mississippi suffers the bombardments of human civilization, deteriorating with each mile. Several factors contribute to its degradation. For one, the river becomes more and more polluted with run-off from the whopping 40 percent of US land that it drains: chemical fertilizers from agriculture, industrial toxins, as well as sewage and waste. By the time it reaches Louisiana, the water is so filthy that the government advises against eating the fish or swimming in the river.