Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. St. Lawrence County is a county located in the U.S. state of New York. As of the 2000 census, the population was 111,931. The county seat is Canton. The county is named for the Saint Lawrence River, which in turn was named for the Catholic saint on whose Feast day the river was discovered. St. Lawrence County is the largest county in New York based on area (New York County is the smallest).