The Clarion River is a tributary of the Allegheny River, approximately 110 mi (177 km) long, in west central Pennsylvania in the United States. It drains a rugged area of the Allegheny Plateau in the Ohio River watershed, flowing through narrow serpentine valleys and hardwood forests.

Cook Forest State Park is a 8,500-acre (3,440 ha) Pennsylvania state park in Farmington Township, Clarion County, Barnett Township, Forest County and Barnett Township, Jefferson County, Pennsylvania in the United States. Located just south of the Allegheny National Forest, the park is a heavily wooded area of rolling hills and mountains along the Clarion River in northwestern Pennsylvania. Cook Forest State Park is known for some of America's finest virgin white pine and hemlock timber stands and was once called the "Black Forest" due to the preponderance of evergreen tree coverage.