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International Highway Bridge

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1962, Steinman, Boynton, Gronquist, and Londson. I-75 over St. Mary's River
  • (Photograph by Balthazar Korab)

Until this bridge was opened in 1962, automobile traffic between the American and Canadian Saults was carried by ferry. In 1935 the Michigan and Ontario governments established an International Bridge Authority to plan and finance a highway bridge to replace the ferry for automobile traffic. More than two decades passed before construction began. The structure, 2.76 miles long, including approaches, has a two-lane roadway 28 feet wide. The bridge comprises a 2,471-foot American approach, a 2,942-foot Canadian approach, and a 9,280-foot river section resting on sixty-two reinforced-concrete piers. A four-span, 1,260-foot-long cantilevered truss crosses the American Navigation Canal. In order not to interrupt navigation, it was erected without falsework through the use of balanced additions of steel members in assembling the two main spans of 540 feet each. The Canadian crossing, a single main span of 430 feet and two side spans of 200 feet each, was simpler to construct.

Writing Credits

Kathryn Bishop Eckert


What's Nearby


Kathryn Bishop Eckert, "International Highway Bridge", [Sault Ste. Marie, Michigan], SAH Archipedia, eds. Gabrielle Esperdy and Karen Kingsley, Charlottesville: UVaP, 2012—,

Print Source

Cover: Buildings of Michigan

Buildings of Michigan, Kathryn Bishop Eckert. Charlottesville: University of Virginia Press, 2012, 554-554.

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