The Casselman River is a tributary of the Youghiogheny River located in western Maryland and southwestern Pennsylvania. It flows approximately 40 miles, starting in the Allegheny Mountains and winding through scenic landscapes, including forests and farmland. The river is known for its clear waters and diverse aquatic life. The Casselman River is popular for recreational activities such as fishing, kayaking, and tubing. It is also home to several historical sites, including the Casselman Bridge, a historic stone arch bridge built in the early 19th century. The river's natural beauty attracts visitors year-round.