St. Lawrence Seaway Treaty

The signing of the St. Lawrence Seaway Treaty in 1932 initiated a series of negotiations that spanned twenty-five years before the United States and Canada agreed on the conditions for constructing the seaway. The seaway’s completion in 1959 established a new level of interaction between the two countries.

Summary of Event

The story of the St. Lawrence Seaway began in 1909, when the United States and Canada signed the Boundary Waters Treaty, Boundary Waters Treaty (1909) which created the International Joint Commission. The commission was charged with implementing joint development of all navigable boundary waters. The St. Lawrence River was first and foremost among these waters. Although most of the river flowed through Canada, it divided the two nations for a 44-mile stretch between the province of Ontario and the state of New York. The St. Lawrence had been an important communications route between Europe and North America since the time of European exploration of the American continent. Because it is the outflow of the Great Lakes, four of which also form the boundary between Canada and the United States (only Lake Michigan is wholly within the United States), it had become a major trade artery for both countries. [kw]St. Lawrence Seaway Treaty (July 18, 1932)
[kw]Seaway Treaty, St. Lawrence (July 18, 1932)
[kw]Treaty, St. Lawrence Seaway (July 18, 1932)
St. Lawrence Seaway Treaty (1932)[Saint Lawrence Seaway Treaty]
Hoover-Bennett Treaty (1932)[Hoover Bennett Treaty]
[g]Canada;July 18, 1932: St. Lawrence Seaway Treaty[08080]
[g]United States;July 18, 1932: St. Lawrence Seaway Treaty[08080]
[c]Diplomacy and international relations;July 18, 1932: St. Lawrence Seaway Treaty[08080]
[c]Laws, acts, and legal history;July 18, 1932: St. Lawrence Seaway Treaty[08080]
[c]Transportation;July 18, 1932: St. Lawrence Seaway Treaty[08080]
Connally, John
Eisenhower, Dwight D.
Hoover, Herbert
[p]Hoover, Herbert;St. Lawrence Seaway Treaty[Saint Lawrence Seaway Treaty]

Before the nations could carry out the commitments expressed in the Boundary Waters Treaty, a number of engineering problems needed to be solved. One of these was passing Niagara Falls, which lies between Lake Erie and Lake Ontario. This problem was addressed by the Welland Canal, Welland Canal which was built in Canadian territory. In the 1820’s, the canal had been dug to a depth of eight feet, and it had been progressively enlarged and deepened during the nineteenth and twentieth centuries. In its course west of Montreal, Canada, the river contained a number of rapids that severely impeded navigation, and there were significant shoals in the section that formed the international boundary between the two countries. Finally, the river’s massive flow offered substantial hydroelectric potential that would require dams or diversions to harvest.

Powerful interests lobbied on both sides of the issue. In favor were the agricultural interests of the Midwest, both in Canada and the United States, that wanted a water-based transportation system (as opposed to a rail system), which would be a cheaper way of sending bulk commodities such as grain. In the 1930’s, the iron and steel industries, especially those in the United States, expected to mine the iron deposits of northern Minnesota’s Mesabi range indefinitely, but by the end of World War II it was clear that these supplies were almost gone. The most promising replacement was the extensive deposits recently discovered in Labrador, and the steel industry realized that it could move these deposits to the plants of the Midwest if ships were able travel down the St. Lawrence River from the Atlantic Ocean and make it at least as far as Lake Erie. Until it became clear that this new source of iron was needed, the steel corporations were not interested in promoting the seaway.

Multiple interests were opposed to the seaway’s development, partly because it would involve major government investments and partly because it would negatively affect their businesses. The railroads of both nations saw the seaway as a competitor and were strongly opposed to its development; prior to the seaway’s completion, many exporters had used the railroads to transport their products to the coasts. The coal industry (of which the railroads were major customers) also opposed the seaway, since it would harm the railroad industry. Ports along the Atlantic coast opposed the seaway because it would enable ships to proceed from the Midwest directly to their destinations elsewhere in the world. Private utilities did not want to compete with government-funded facilities that produced hydroelectric power, and so they were also opposed.

Major political interests also opposed the seaway’s development. In Canada, the dominant political forces in both Ontario and Quebec opposed ceding power to the federal government, arguing instead that Canada’s constitution gave control over boundary waters to the provinces. In the United States, progress on the issue was stymied by senators from the South; these senators, notably Tom Connally of Texas, were able to prevent approval of the treaty, which required a positive vote of two-thirds of senators before it could go into effect. Despite the fact that every president from Herbert Hoover to Dwight D. Eisenhower supported the idea, opposition from the Senate could not be overcome for more than twenty years.

There was also the question of local versus federal control over any hydroelectric power developed in conjunction with the seaway’s construction. In Canada, the federal government could not proceed with a plan to develop the seaway until the premier of the province of Ontario was brought on board. This issue was resolved by two 1941 agreements between Ontario and Canada’s federal government, in which the federal government assumed responsibility for any navigational improvements in the St. Lawrence and Ontario was put in charge of any hydroelectric capabilities that were developed in conjunction with the seaway.

Resolving the hydroelectric issue in the United States was harder, because New York State wanted its own power authority to control its share of the hydroelectric power, and it could do so only with the approval of the Federal Power Commission Federal Power Commission (FPC) in Washington, D.C. Opponents of the seaway remained in control of the FPC almost to the end of negotiations, but finally President Eisenhower overrode the FPC’s opposition by arguing that the seaway could be a useful tool in the U.S. defense arsenal.

Once the Canadians had resolved their differences about the seaway, they became its chief proponents in the post-World War II era. As long as it was impossible to resolve congressional opposition to U.S. participation, the Canadians had to develop an alternative solution. They proposed that Canada should develop the seaway alone, which became possible when most of the construction costs were shifted from the navigational improvements to developing the hydroelectric capabilities. Canada created its own St. Lawrence Seaway Authority, which was in charge of the development. Canadian officials agreed, however, that this was a less desirable solution than joint development, and it was hoped that this prospect would spur the United States to action.


Efforts to build the St. Lawrence Seaway spanned the first half of the twentieth century in both the United States and Canada. The seaway’s completion was a monument to a new level of cooperation between the two North American powers. Its construction indicated the shifting priorities of both countries, even though from a population standpoint Canada remained about one-tenth the size of the United States. The joint creation of the St. Lawrence Seaway inaugurated a series of cooperative ventures of the two largest North American powers, and its economic and political success led to the nations’ increased regionalization.

The combination of shifting many of the costs to the hydroelectric development at last moved Congress to act, and in the spring of 1954, Congress voted to create the St. Lawrence Seaway Development Corporation, which would work jointly with Canada’s St. Lawrence Seaway Authority in developing the project. FPC approval of the New York State Power Authority was also secured. Work immediately began on construction of the seaway improvements to navigation-related matters and the creation of the hydroelectric elements. The entire project was built in the period 1954-1958, and it opened on June 26, 1959, in a formal ceremony presided over by Queen Elizabeth of England, who represented Canada, and President Eisenhower, who represented the United States. St. Lawrence Seaway Treaty (1932)[Saint Lawrence Seaway Treaty]
Hoover-Bennett Treaty (1932)[Hoover Bennett Treaty]

Further Reading

  • Bothwell, Robert. A Short History of Ontario. Edmonton, Alta.: Hurtig, 1986. Describes the negotiations by which Ontario and the Canadian federal government resolved their differences.
  • MacLennan, Hugh. The Rivers of Canada. Toronto: Macmillan of Canada, 1977. Describes the history of the St. Lawrence and clarifies its enormous strategic significance.
  • Rea, K. J. The Prosperous Years: The Economic History of Ontario. Toronto: University of Toronto Press, 1985. A thorough survey of economic developments in Ontario, the most developed part of Canada.
  • Willoughby, William R. The St. Lawrence Waterway: A Study in Politics and Diplomacy. Madison: University of Wisconsin Press, 1961. An exhaustive account of the attempts, on both sides of the border, to construct the waterway.

King Era in Canada

Halibut Treaty

Canada Enacts Depression-Era Relief Legislation

Formation of the British Commonwealth of Nations

Ottawa Agreements

Arbitration Affirms National Responsibility for Pollution

King Returns to Power in Canada

Reciprocal Trade Act

Ogdensburg Agreement