The St. Clair rail tunnel was the first rail tunnel ever to pass under a river.
The tunnel was an engineering marvel in its day, achieved through the development of original techniques for excavating in a compressed air environment.
It joins Sarnia, Ontario with Port Huron, Michigan.
From October 30, 1982, until April 23, 2004, the International, operated jointly by VIA Rail and Amtrak, crossed St. Clair tunnel during runs between Chicago and Toronto.
