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.

Barge traffic is increasing, but some argue the Mississippi is already overburdened by navigation demands.

The Mississippi valley was the site of the largest urban populations in pre-Columbian America, the Cahokian mound-building states. The river was a crucial transportation link connecting the middle United States to the rest of the world in the 19th century. New Orleans became the hub of this vast commercial system made possible by the introduction of steamboats that could move against the river's current. This “destruction of space by time” greatly accelerated travel throughout the region and connected forestry and farming across a vast expanse to markets.

The steamboat revolution also resulted in hazardous travel on the Mississippi, as the large number of trees pulled into the river by erosion formed many snags that were hard to detect and readily sank boats that ran into them. In the 1830s the entrepreneur Henry Shreve operated a fleet that pulled up many of these snags and directed crews of loggers who cleared riverside trees. This widespread deforestation made steamboat navigation much safer while it accelerated the rate of soil erosion along the river, already increased by expanding agriculture and land clearing throughout the river's eastern reaches. Thus by the 1840s the river was already greatly shaped by human action, but was certainly not tamed.

Levees along the river were constructed from the time of French colonization of Louisiana in the 18th century, and gradually expanded in length and height. Periodic severe floods overwhelmed levees, leading to increasing federal involvement. In 1849 and 1850, the Swamp Land Acts gave federal land to the states for the purpose of funding levee improvements to reclaim the vast swamps in the river valley and protect existing development.

Proponents of a “levees only policy” won a long and sometimes bitter engineering argument on the proper means of controlling flooding. Levees-only proponents argued against the maintenance of multiple outlets for river overflow because keeping the river in a narrow channel would keep the river scoured of obstructions and deepen it to accommodate floodwaters. The levees-only approach also served to maximize the area that could be reclaimed from swamps for plantation agriculture and coincided with the confidence proponents felt that science and technology could make the river do their bidding.

Such confidence in engineering was bolstered by the success of James Eads in 1876 opening up the sandbars that blocked deep draft ship access to the mouth of the river. By means of a jetty that constricted the river's flow at its mouth, the river pushed away the bars and opened the channel without costly dredging, allowing for an explosion of shipping tonnage at the port of New Orleans that placed that city on par with the largest ports in the world.

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