|Carl Venzke posted|
The Incan Superior, loaded with rail cars, navigates the Duluth Ship Canal as it leaves Duluth for Thunder Bay. (Image: Courtesy of Historical Collections.)
The end came because Canadian National Railway built a land-based railroad route which was a less-expensive method of transport. And a "new U.S. federal tax was to go into affect, applied to each rail car carried over the water between the two countries by vessels such as the Incan Superior. The tax rendered the vessel unprofitable to operate, and the entire program was quickly abandoned."
The ship had a second life providing rail and car ferry service between Vancouver and Nanaimo on Vancouver Island.
So the US didn't get any tax revenue, and jobs were lost. That was a loose-loose.
The 2005 SPV Map shows the ferry used the southern entry channel and docked here. But the photo above shows it using the northern entry channel. ZenithCity mentioned that the maiden voyage did use the southern entrance.
I could find no evidence of the slip, apron, or rails where the SPV Map showed the CP route terminating. If it ran until 1992, I would expect to see something since this land is undeveloped.