St. Clair Tunnel, Under St. Clair River between Port Huron, MI, & Sarnia, ON, Canada, Port Huron, St. Clair County, MI

Significance: The St. Clair Tunnel was the first full-sized subaqueous tunnel built in North America. Joseph Hobson, the Chief Engineer, successfully combined three significant new technologies a tunnel shield driven by hydraulic rams; a cast iron tunnel lining; and the use of a compressed air environment. This tunnel eliminated a major bottleneck in the rail transportation system linking the American midwest with its eastern markets.
Survey number: HAER MI-67
National Register of Historic Places NRIS Number: 70000684