The Cheat River is a 78.3-mile-long (126.0 km) tributary of the Monongahela River in eastern West Virginia and southwestern Pennsylvania in the United States. Via the Ohio River, the Cheat and Monongahela are part of the Mississippi River watershed. Owing to the ruggedness of the Allegheny Mountains, a portion of which it drains, the Cheat remains largely remote with few settlements or developments along its banks.