Just to put (hopefully) an end to the discussion over Sault Ste. Marie and the notion of whether or not there are/were "falls" there.
I think it's an idea of perception and definition. Several have come on and posted that they've been there, and there are no falls there. Now, if you are talking about a large, deep drop off-- as an example, visualize one of the most famous falls, Niagara Falls-- there isn't one there, and there never was. Sault Ste. Marie (literally, in old French "Jumps/rapids of St. Mary ") was originally a series of what most today would call "rapids", but also can correctly be called "falls", as the river falls 21 feet in a short stretch. It is very similar to the old Falls of the Ohio River which were located near Louisville, KY.
Like the Falls of the Ohio, the need for river navigation called for the construction of dams and locks, which almost completely eliminated the natural state of the rapids or falls, which for both rivers used to extend from bank to bank. At Sault Ste. Marie, the center area between the Canadian locks and American locks still has a series of rapids, though with changes in water flow due to the locks, they are a shadow of their original self.