I-75 (Int. Hwy.) / St. Mary's River

MDOT Historic Bridge Chippewa County I-75 St. Mary's River

County: Chippewa

City/Township: Sault Ste. Marie

Location: I-75 (Int. Hwy.) / St. Mary's River

Year Built: 1962

About this Bridge:
This is one of Michigan's five monumental bridges.  The twin cities of Sault Ste. Marie in Michigan and Ontario were linked by a railroad bridge in 1887, but automobile traffic between the cities was carried by ferry until this bridge was opened in 1962. An International Bridge Authority was created by the Michigan State Legislature and passed before construction was begun.

It was designed by the firm of Steinman, Boyton, Gronquist, and London of New York and cost twenty million dollars. This bridge was an ambitious project because it crossed two navigation canals and the St. Mary's River.Overall, the bridge is 2.76 miles long, including approaches, and provides a two lane roadway 28 feet wide. The Main spans had to be erected without the use of falsework so as not to obstruct traffic through the American and Canadian Locks. This was done through the balanced addition of steel structural members on the main spans.