A 20-cent commemorative stamp recognizing the 25th anniversary of the opening of the St. Lawrence Seaway was issued June 26, 1984, in Massena, New York. The First Day of Issue ceremony was held at the town hall. A similar stamp was issued the same day by Canada Post Corporation.
Both the US and Canada stamps were designed by Ernst Barenscher of Kings City, Ontario. The US stamp graphically depicts an aerial view of the overall route of the seaway, and the Canada stamp features a profile view of the entire inland waterway made navigable by the seaway. The modeler of the US stamp was Richard Sennett.
The United States and Canada completed the St. Lawrence Seaway in 1959. The 2,342-mile waterway, stretching from the Atlantic Ocean to Duluth, Minnesota, opened the industrial and agricultural heartland of North America to deep-draft ocean vessels.
The American Bank Note Company printed the St. Lawrence Seaway stamp. The numbering system, as with all the stamps printed by the firm, features the letter "A" as a prefix. The US stamp was printed in the photogravure process, with fifty stamps per pane.
By agreement between the two postal administrations, the Canada stamp was sold by the US Postal Service at a price of thirty-two cents, and the US stamp was sold in Canada by Canada Post Corporation. Packets prepared by Canada containing either an individual plate number block of four or four-position plate number blocks (sixteen stamps) were sold by the US Postal Service for $1.28 and $5.12, respectively.
The US Postal Service sold both versions of the St. Lawrence Seaway stamp first day cover prepared by Canada Post Corporation. The versions feature an appropriate design on the left side. The single cover bore the Canada stamp and cancellation only, and the combination cover had both the Canada stamp and the US stamp affixed, each bearing the cancellation of the respective country. They were sold for fifty-two cents and seventy-two cents, respectively. These fees included a twenty-cent charge for the cover.
Canada's stamp, pre-packaged plate number blocks, and covers were sold in Massena, New York, on June 26 only. Following that, they were sold by mail order from the Philatelic Sales Division and at the L'Enfant Plaza Philatelic Center in Washington, DC, until December 31. The first day covers only were available at 113 Philatelic Centers in the United States during the same period.
The US Postal Service was authorized to apply the Canadian first day of issue cancellation to Canada's stamp on a hand back basis in Massena on June 26 only and by mail order from Massena until July 26, thirty days after the issue date. However, customers placing mail orders for the Canadian stamp and cancellation on their covers also had to bear the US stamp in the upper right corner of the envelope to allow for the cover's return by mail. Mail orders for covers bearing only the Canadian stamp were not accepted. Canada also was authorized to apply the US first day of issue cancellation to US stamps in Canada.
Neither the US nor Canada stamp had the first day of issue cancellation of the other country applied to it. The US cancellation was applied to the US stamp only, and the Canadian cancellation was applied only to that country's stamp. However, covers bearing the stamps of both countries adjacent to one another, such that one of the country's cancellations would strike both stamps, were canceled with either cancellation, according to the customer's request.
Postal Bulletin (May 24, 1984).