Without question the Nation's principal river, the Mississippi, is the main stem of a network of inland navigable waterways maintained by the U.S. Army Corps of Engineers, which form a system of about 12.350 miles in length, not including the connecting Gulf Intracoastal Waterway (of around 1,300 miles) and its connecting inland and Gulf Coast streams. This giant waterways system includes the Ohio, Missouri, Illinois, Arkansas, and Tennessee Rivers, among others. It extends into the agricultural midwest and the industrial east, making Memphis, Vicksburg, and New Orleans close neighbors of Pittsburgh, Kansas City, and Chicago.

The port of New Orleans is the number one grain port in the world and the number one port in the United States.

The rapid growth in river traffic may be traced to many interdependent factors. One of the most important is the great improvement in the towboats and barges themselves. Carefully conducted research projects and much prototype experimentation have accounted for significant developments in transportation methods. Modern steel barges have a capacity of three or four times that of one packet boat. The average modern steam or diesel towboat may push as many as twenty 1,000-ton steel barges at one time.

Integrated tows, developed several years ago, are becoming more and more numerous on the Mississippi. Made up of a bowpiece, a number of square-end barges, and a towboat, the entire unit is lashed together to form one streamlined vessel. The integrated tows vary in size; but one of the largest is nearly 1,200 feet long-Ionger than the largest ocean liner afloat. This tow often carries 200,000 barrels (35,000 tons) of petroleum products.

Towboats have become larger and much higher powered. For example, in the recent past the average towboat had about 500 horsepower. Today, the average is about 3,000 horsepower, with some towboats operating with more than 10,500 horsepower. Powered by three marine diesel engines - each rated at 3,500 horsepower - the new boats measure 190 by 54 by 12-1/2 feet. They are driven by three 10-foot-diameter five-bladed stainless steel propellers, housed in Kort nozzles. These boats are working the fast-flowing, lock-free lower Mississippi River where tows of 40 or more barges with total carrying capacity of 50,000 to 60,000 tons of cargo consisting primarily of steel, ores, grain, petroleum products, and chemicals can be handled.

Waterborne commerce on the Mississippi has risen from 30 million tons in 1940 to approximately 400 million short tons in 1984. This heavy commercial traffic includes grains, coal and coke, petroleum products, sand and gravel, salt, sulphur and chemicals, among others.