St. Lawrence Seaway

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Lore & Background

The St. Lawrence Seaway was preceded by several canals. In 1871, locks on the St. Lawrence allowed transit of vessels 186 ft long, 44 ft 6 in wide, and 9 ft deep. The First Welland Canal, constructed between 1824 and 1829, had a minimum lock size of 110 ft long, 22 ft wide, and 8 ft deep, but it was generally too small for larger oceangoing ships. The Welland Canal's minimum lock size increased through four generations, reaching 766 ft long, 80 ft wide, and 30 ft deep for the current Fourth Welland Canal. First proposals for a binational comprehensive deep waterway were made in the 1890s. A 1932 treaty of intent was signed by Prime Minister Mackenzie King and the U.S. representative, but it failed to gain the necessary two-thirds vote for ratification in the U.S. Senate on March 14, 1934. Later attempts in the 1930s came to naught due to opposition by the Ontario government of Mitchell Hepburn and the government of Quebec. On September 28, 1951, Canadian Prime Minister Louis St. Laurent advised U.S. President Harry S. Truman that Canada would build a seaway alone; the Canadian Parliament authorized the founding of the St. Lawrence Seaway Authority on December 21, 1951. The first positive action to enlarge the seaway was taken on May 13, 1954, when U.S. President Dwight D. Eisenhower signed the Wiley-Dondero Seaway Act. Groundbreaking ceremonies took place in Massena, New York, on August 10, 1954. The seaway opened in 1959 and cost C$470 million, $336.2 million of which was paid by the Canadian government. Elizabeth II, Queen of Canada, Prime Minister John Diefenbaker, and President Eisenhower formally opened the seaway on June 26, 1959, with a short cruise aboard the royal yacht HMY Britannia after addressing crowds in Saint-Lambert, Quebec. 22,000 workers were employed at one time or another on the project, a 3,700-kilometre-long superhighway for ocean freighters.

Reader's Guide

The St. Lawrence Seaway's significance lies in its transformation of North American trade by allowing oceangoing vessels to reach the industrial and agricultural heartland of the continent. Its construction overcame decades of political and economic opposition, including resistance from Atlantic and Gulf Coast harbor interests and railroad associations. The seaway's opening is often credited with making the Erie Canal obsolete, though the source notes that by the turn of the 20th century, the Erie Canal had already been largely supplanted by the railroads. The seaway was heavily promoted by the Eisenhower administration, which had been concerned with a lack of US control. Port of Milwaukee director Harry C. Brockel forecast just before the Seaway opened in 1959 that 'The St. Lawrence Seaway will be the greatest single development of this century in its effects on Milwaukee's future growth and prosperity.' Lester Olsen, president of the Milwaukee Association of Commerce, said, 'The magnitude and potential of the St. Lawrence Seaway and the power project stir the imagination of the world.' Great Lakes and seaway shipping generates $3.4 billion in business revenue annually in the United States. In 2002, ships moved 222 million tonnes of cargo through the seaway. Overseas shipments, mostly of inbound steel and outbound grain, accounted for 15.4 million tonnes, or 6.9%, of the total cargo moved. In 2004, seaway grain exports accounted for about 3.6% of U.S. overseas grain shipments. In a typical year, seaway steel imports account for around 6% of the U.S. annual total. The toll revenue obtained from ocean vessels is about 25–30% of cargo revenue. The seaway remains a key binational infrastructure project, managed jointly by Canadian and U.S. authorities and marketed as 'Highway H2O.'

Did You Know?

• The seaway's legal boundary runs from Montreal, Quebec, to Lake Erie, and includes the Welland Canal.
• 22,000 workers were employed at one time or another on the project, a 3,700-kilometre-long superhighway for ocean freighters.
• Elizabeth II, Queen of Canada, Prime Minister John Diefenbaker, and President Eisenhower formally opened the seaway on June 26, 1959, with a short cruise aboard the royal yacht HMY Britannia.
• In 2002, ships moved 222 million tonnes of cargo through the seaway.
• The need for cheap haulage of Quebec-Labrador iron ore was one of the arguments that finally swung the balance in favor of the seaway.

Physical Scope and Engineering Design

The St. Lawrence River portion of the seaway is not a continuous waterway; rather, it consists of several stretches of navigable channels within the river, a number of locks, and canals along the banks of the St. Lawrence River to bypass several rapids and dams. A number of the locks are managed by the St. Lawrence Seaway Management Corporation in Canada, and others in the United States by the Great Lakes St. Lawrence Seaway Development Corporation; the two bodies together advertise the seaway as part of 'Highway H2O'. The section of the river from Montreal to the Atlantic Ocean is under Canadian jurisdiction, regulated by the offices of Transport Canada in the Port of Quebec. The seaway legally extends from Montreal, Quebec, to Lake Erie, and includes the Welland Canal. Ships from the Atlantic Ocean are able to reach ports in all five of the Great Lakes via the Great Lakes Waterway, as far inland as Duluth, Minnesota, at the western end of Lake Superior.

The Decades-Long Diplomatic Battle

The seaway did not emerge from a single bold decision but from more than half a century of stalled negotiations. Initial binational proposals surfaced in the 1890s, and by the 1920s both the Wooten-Bowden Report and the International Joint Commission endorsed the concept. Yet Prime Minister Mackenzie King's reluctance, fueled by Quebec opposition, derailed a 1932 treaty of intent; the U.S. Senate voted in favor in 1934 but fell short of the two-thirds threshold. The 1930s saw repeated failures as Ontario's Mitchell Hepburn government and Quebec blocked progress. A 1938 resumption of talks produced substantial agreement by January 1940, and Roosevelt and King signed an executive accord in 1941—only for Congress to withhold assent. After 1945, toll proposals failed to sway Washington. The breakthrough came when Canada, impatient and energized by Ontario's hunger for hydroelectric power, declared in September 1951 that it would build the waterway alone. That nationalist surge finally compelled the United States to act, culminating in Eisenhower's signature on the Wiley-Dondero Seaway Act in May 1954.

The Welland Canal's Four Generations

The Welland Canal, a critical link connecting Lake Erie to Lake Ontario, underwent four distinct construction phases that trace a century of escalating engineering ambition. The First Welland Canal, built between 1824 and 1829, offered a minimum lock of just 110 feet long, 22 feet wide, and 8 feet deep—dimensions that proved too restrictive for larger oceangoing vessels. The Second Welland Canal widened the minimum lock to 150 feet by 26.5 feet with a 9-foot depth. The Third generation pushed the envelope further, reaching 270 feet in length, 45 feet in width, and 14 feet of depth. The current Fourth Welland Canal represents the most dramatic leap: its locks measure 766 feet long, 80 feet wide, and 30 feet deep, accommodating the full size of modern ocean-going freighters. By 1871, locks elsewhere on the St. Lawrence already permitted transit of vessels up to 186 feet long, 44 feet 6 inches wide, and 9 feet deep, underscoring how the Welland's early iterations lagged behind the broader river system's capacity. Each successive rebuild reflected the growing commercial demand for a waterway capable of handling the largest ships calling at Great Lakes ports.

Economic Stakes and the Hydro-Navigation Nexus

Proponents of the seaway argued that a nautical link between the Atlantic and the Great Lakes would unlock the economies of the interior by enabling oceangoing ships to carry grain and other commodities directly to export markets. In the 1930s, grain shipments to Europe were a vital pillar of the national economy, and John C. Beukema, head of the Great Lakes Harbors Association, personally lobbied President Roosevelt in 1936 to secure his backing. Yet the project faced fierce resistance from Atlantic and Gulf Coast harbor interests and from railroad associations that profited from hauling freight between coastal ports and Great Lakes cities. A second, inseparable thread ran through every proposal: the hydropower component. Developers and governments alike believed that the deeper water created by a hydroelectric project was essential to make the seaway channels viable for ocean-going tonnage. This coupling meant the Moses-Saunders Power Dam, which would alter water levels, required bilateral cooperation between Ontario and New York. The need for inexpensive transport of Quebec-Labrador iron ore became one of the decisive economic arguments that finally tipped the balance toward construction.