The Cowanesque River is a 41.4-mile-long (66.6 km) tributary of the Tioga River in Potter and Tioga counties, Pennsylvania, and Steuben County, New York, in the United States. It joins the Tioga River soon after crossing from Pennsylvania into New York, near the borough of Lawrenceville, Pennsylvania. The name of the Cowanesque River is of Native American origin, derived either from Go-wan-is-que ("briary or thorn bushy"), or from Ka-hwe-nes-ka ("on the long island").