Following the War of 1812 between the United States and Britain, the push was on for westward expansion. The route along the St. Lawrence River to Lake Ontario did not suit the U.S., for it was controlled mostly by Canada. Moreover, there was as yet no way past Niagara Falls into Lake Erie.

So the great Erie Canal was cut. It was 363 miles (584 kilometers) long, with 82 locks, and ran from Albany on the Hudson River north of New York city to Buffalo on Lake Erie. Opened in 1825, the Erie Canal was a commercial success from the start. Consequently, in foreign trade, New York city took ascendancy over Baltimore, Boston and Philadelphia. The Erie Canal contributed to making New York one of the world’s greatest seaports.

Other concerns focus on the imbalance man-made waterways can cause in the natural creation. The Erie and Welland Canals opened the way for the sea lamprey, an eellike native of the North Atlantic, to invade the Great Lakes, where it decimated populations of commercially valuable fish.