St. Lawrence River Facts
The St. Lawrence River is one of the largest rivers in North America. It is also the outflow for the entire Great Lakes system. Learn additional information about the River ecosystem here.
The River flows 744 miles from Lake Ontario into the world’s largest estuary, the Gulf of St. Lawrence. However, 114 of the 744 miles of the River are located in New York State.
The River is 250 feet at its deepest point.
Flowing through both Canadian and US lands, the St. Lawrence River is a bi-national waterway, providing drinking water to local municipalities on both sides of the River and a vital tourism-based economy to local towns.
Fun River Facts
- The St. Lawrence River is also known as Highway H2O
- It’s the second largest river in Canada and the third largest in the U.S.
- The River is home to approximately 45 million people
- The Gulf of the St. Lawrence is the largest estuary in the world
- The St. Lawrence River has a discharge rate of 347, 849 cubic feet of water per second
- The River drops 226 feet between Lake Ontario and Montreal
For additional information about the St. Lawrence River and Thousand Islands:
- Great Lakes Guide – Learn about the region’s ecology, history, and culture from the Great Lakes Guide community as we bring together personal stories, indigenous knowledge, local history, and scientific discoveries.
- New York State Department of Environmental Conservation – Learn about the St. Lawrence River watershed and view a map.
- Thousand Islands Life – An on-line magazine devoted to the history and culture of the Thousand Islands region.