OTD: St. Lawrence Seaway leads to iconic error

On today’s date in 1957, the Department of Transport vessel CGS Grenville became the first ship to navigate any section of the St. Lawrence Seaway as it passed through the Iroquois Lock, which was completed in Cornwall, Ont., only a few weeks earlier.

Officially opened to navigation in 1959, the seaway is a deep draft waterway extending 3,700 kilometres from the Atlantic Ocean to the head of the Great Lakes, “in the heart of North America,” according to the seaway website. Built as a bi-national partnership between Canada and the U.S., it continues to operate as such.

“Ranked as one of the outstanding engineering feats of the twentieth century, the St. Lawrence Seaway includes 13 Canadian and 2 U.S. locks.”

The seaway was conceived as early as the late 1800s, after which time several locks and canals allowed access to smaller vessels.

The seaway is widely considered as one of the most outstanding engineering feats of the previous century. (Photo by Great Lakes St. Lawrence Seaway System)


Construction of the 306-kilometre stretch of the seaway between Montreal and Lake Ontario is recognized as one of the most challenging engineering feats in history. Seven locks were built in the Montreal-Lake Ontario section of the seaway – five Canadian and two U.S. – in order to lift vessels to 75 meters above sea level.

The 44-kilometre Welland Canal is the fourth version of a waterway link between Lake Ontario and Lake Erie, first built in 1829. The present canal was completed in 1932, deepened in the 1950s as part of the seaway project and further straightened in 1973.

Today, its eight locks – all Canadian – lift ships 100 metres over the Niagara Escarpment.

While no date has been scheduled, the multi-national authority has plans to expand the seaway in the next 20 years to accept vessels measuring up to 320 metres.


The regular issue of the St. Lawrence Seaway stamp has both the central blue design and the red text facing the correct way.

The famed St. Lawrence Seaway stamp was issued on June 26, 1959, coinciding with the opening of the St. Lawrence Seaway by Queen Elizabeth II and U.S. President Dwight D. Eisenhower.

A joint issue between Canada and the U.S., the stamp marked the first collaboration between the two countries’ postal services.

The planning and production of the stamps to commemorate the event took almost as long as the construction of the seaway itself with proposals coming forward in 1954 in the U.S. and in 1956 in Canada.

One of Canada’s most famous philatelic errors, the St. Lawrence Seaway invert was also Canada’s first major printing error. The stamp was printed with two colours of ink (red and blue), each of which required separate engraving plates. On their second pass through the printing press, some of the stamp panes were inserted backwards and the red text was printed upside down.

The first report of the discovery of the Seaway invert was when a young office boy from the Marlborough Hotel in Winnipeg purchased 30 stamps from a post office outlet in the Eaton store on Aug. 20, 1959. It’s believed more than 200 examples exist today. Mint singles are listed in the Unitrade Specialized Catalogue of Canadian Stamps at $16,000.

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