Hot off the press, here is a reading on St. Lawrence Seaway along with its accompanying vocabulary-building and comprehension worksheet. This is a good short, general history of the seaway.
That said, comparisons with the Erie Canal come up in the text. This might be a good set of documents to serve as a comparative study of these two trade routes. In my experience, many high-stakes tests in high school are about technological advances and their effect on society, culture, and, in this case, trade.
If you find typos in these documents, I would appreciate a notification. And, as always, if you find this material useful in your practice, I would be grateful to hear what you think of it. I seek your peer review.
Mark's Text Terminal 