the Erie Canal was one of the boldest and largest construction projects of it's time and most people don't realize it's a direct route from Chicago to NYC, opening up Chicago as a major world player because it linked the western and central train networks into not only a cheaper route to the east, but also the Atlantic Ocean.
The St. Lawrence seaway did the same, through Canada. The Great Lakes have, if you don't count the locks, an uninterrupted water connection to the Atlantic.
