The St. Lawrence River is a major waterway in North America, flowing from Lake Ontario to the Gulf of St. Lawrence. It serves as a natural border between the United States and Canada, stretching approximately 1,197 kilometers (744 miles). The river is crucial for trade and transportation, connecting the Great Lakes to the Atlantic Ocean. The St. Lawrence River is also known for its rich biodiversity, supporting various fish species and wildlife. It features several important cities along its banks, including Montreal and Quebec City. The river plays a significant role in the region's economy, recreation, and cultural heritage.