Penetrating 3,540 kilometers (2,200 miles) into interior North America, the Great Lakes-St. Lawrence Sea-way navigation system, completed in essentially its present form in 1959, was regarded as one of the great engineering accomplishments of the 20th century and an outstanding example of international cooperation. . It was intended to remove much of the disadvantage of the continental interior in importing and exporting overseas. It was also designed to meet the increasing needs for electric power on both sides of the United States-Canada border.
             The discovery and prospective exploitation of the iron ore north of the Gulf of St. Lawrence made the seaway project politically practicable. The main bottleneck in the chain of waterways was the 177 kilometers (110 miles) above Montreal. Improvement of that stretch was authorized by the Canadian Parliament in 1951 and by the U.S. Congress in 1954. Construction commenced in August 1954, and the route was opened for through traffic in April1959. Navigation benefits and costs, and hence toll receipts, were originally to be 71 percent Canadian and 29 percent United States; these proportions were slightly changed later. The Canadian portion of the waterway is maintained and operated by the St. Lawrence Seaway Authority, and the United States portion by the St. Lawrence Seaway Development Corporation.
             Seaway traffic consists of both bulk and general cargo, in contrast to internal Great Lakes traffic, which is almost entirely bulk cargo: grain, iron ore, coal, lime-stone, chemicals, and petroleum products. Seaway traffic is dominated by down bound grain, mostly for export from Canada and the United States, with lesser volumes of up-bound iron ore
             Many factors contribute to the long-term decline of seaway traffic. An important trend is the shift in the direction of b
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