/ Great lake boats, a good video #471
I can't say what the St Clair river tonnage is but the Soo's locks average is 80 million tons per year. The larger 1000ft boats can move more than 70,000 tons per trip when the lakes are full. Whereas the 750ft boats are a sparsity 30,000.Some of them look like race cars sliding around a turn in the current.
Hard to imagine how many tons of material move through there in a day.
The sailing ship didn't seem to be making very good headway going upstream.