December 7, 1891
A rail tunnel that had been built underneath the St. Clair River as a new transportation route between Canada and the United States was opened to passengers. This tunnel was specifically constructed to connect the town (now city) of Sarnia in the Canadian province of Ontario with the city of Port Huron in Michigan.
The entity in charge of building this structure was the St. Clair Tunnel Company, part of the Grand Trunk Railway (GTR). The executive management of GTR sought to have the tunnel installed so that it could provide a link with the Chicago and Grand Trunk Railway, a GTR subsidiary in the Midwestern United States. (These railroads ultimately became part of the present-day Canadian National Railway.) The tunnel was opened for train travel for passengers more than 11 weeks after it had first started serving freight traffic.
The St. Clair Tunnel, which is featured in above postcard image, was the first large-scale subaqueous rail tunnel in North America. This structure had the additional distinction of being the first underwater tunnel to connect two countries. With a length of 6,025 feet (1,836 meters) portal to portal, it was also the longest underwater tunnel constructed up to that time.
James Hobson, a Canadian surveyor and railway engineer, was in charge of designing and building the St. Clair Tunnel. This tunnel was hand-dug by workers from both ends. To help reduce the major risks posed by this type of manual labor, a tunneling shield that been developed by American inventor Alfred Ely Beach was put to use during the early stages of the project. This tunneling shield served as overhead protection from any falling materials or potential cave-ins while workers excavated through the ground beneath the river.
This tunnel remained in service until 1994, when it was replaced by a new St. Clair Tunnel that had been built nearby. The original tunnel, which can still be seen at that location today, was designated a Civil Engineering Landmark by both the Canadian and American Societies of Engineers. It has also been declared a U.S. National Historic Landmark.
For more information on the original St. Clair Tunnel and its successor, please check out https://en.wikipedia.org/wiki/St._Clair_Tunnel