The ship canal did not exist in the 1800's it was built in the early 1900's.

In the 1800's there was a small stream that ran along the path of the ship canal from Fremont to Shilshole. Lake Union drained out in a stream thorough Belltown. There as a little log flume that cut between Lake Washington and Lake Union called the "Canoe Pass". Lake Washington drained out to the Green at Renton, through a river called the Black River. The Cedar entered the Black near Renton Airport.

Lake Washington was 7 feet higher, and Lake Union the height it is now. During the construction of the Locks, a coffer dam broke, and Lake Union was tidal for a little more than a day.

For images of this, see: http://content.lib.washington.edu/neighborhoods/more-info.html
_________________________
Give a man a fish, and you'll feed him for a day; give him a religion, and he'll starve to death while praying for a fish.