The Chemung River is a tributary of the Susquehanna River, approximately 46.4 miles (74.7 km) long, in south central New York and northern Pennsylvania in the United States. It drains a mountainous region of the northern Allegheny Plateau in the Southern Tier of New York. The valley of the river has long been an important manufacturing center in the region but has suffered a decline in the late 20th century.

The Susquehanna River is a major river located in the Mid-Atlantic region of the United States, overlapping between the lower Northeast. At 444 miles (715 km) long, it is the longest river on the East Coast of the United States. By watershed area, it is the 16th-largest river in the United States, and also the longest river in the early 21st-century continental United States without commercial boat traffic.