The St. Clair Tunnel

Near the Port Huron Amtrak station is the St. Clair Tunnel.  This is the train tunnel that connects Port Huron to Sarnia. 

The St. Clair Tunnel Company first opened in 1891.  This was the first full-size subaqueous tunnel built in the United States.  In this case, full-size meant that a train could run through it.  The tunnel was used by the Grand Trunk Railway to connect with Chicago and Grand Trunk Railway (which would later become Grand Trunk Western).  Prior to the construction of the tunnel, Grand Trunk had to use ferries to cross the St. Clair.

The tunnel was designed by Joseph Hobson and was a little over 6000 feet long.  Many new techniques were developed in constructing this tunnel.

Apparently, there was an attempt to sabotage this during World War I.

After World War II, train cars started to get larger and Canadian National (which took over the Grand Trunk) was forced to use ferries again.  It wasn't until the 1990's that the current larger tunnel was built.