The Chemung River is a tributary

Tributary

A tributary or affluent is a stream or river that flows into a main stem river or a lake. A tributary does not flow directly into a sea or ocean...

 of the Susquehanna River

Susquehanna River

The Susquehanna River is a river located in the northeastern United States. At long, it is the longest river on the American east coast that drains into the Atlantic Ocean, and with its watershed it is the 16th largest river in the United States, and the longest river in the continental United...

, approximately 46.4 miles (74.7 km) long, in south central New York

New York

New York is a state in the Northeastern region of the United States. It is the nation's third most populous state. New York is bordered by New Jersey and Pennsylvania to the south, and by Connecticut, Massachusetts and Vermont to the east...

 and northern Pennsylvania

Pennsylvania

The Commonwealth of Pennsylvania is a U.S. state that is located in the Northeastern and Mid-Atlantic regions of the United States. The state borders Delaware and Maryland to the south, West Virginia to the southwest, Ohio to the west, New York and Ontario, Canada, to the north, and New Jersey to...

 in the United States

United States

The United States of America is a federal constitutional republic comprising fifty states and a federal district...

. It drains a mountainous region of the northern Allegheny Plateau

Allegheny Plateau

The Allegheny Plateau is a large dissected plateau area in western and central New York, northern and western Pennsylvania, northern and western West Virginia, and eastern Ohio...

 in the Southern Tier

Southern Tier

The Southern Tier is a geographical term that refers to the counties of New York State west of the Catskill Mountains along the northern border of Pennsylvania. It is a loosely defined term that generally includes the counties that border Pennsylvania west of Delaware County inclusive...

 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.
It is formed near Painted Post

Painted Post, New York

Painted Post is a village in Steuben County, New York, United States. The village is in the town of Erwin, west of the city of Corning. The population was 1,842 at the 2000 census. The name comes from a painted and carved post found by explorers at the junction of three local rivers...

 in Steuben County

Steuben County, New York

Steuben County is a county located in the U.S. state of New York. As of the 2010 census, the population was 98,990. Its name is in honor of Baron von Steuben, a German general who fought on the American side in the American Revolutionary War, though it is not pronounced the same...

, just west of Corning

Corning (city), New York

Corning is a city in Steuben County, New York, United States, on the Chemung River. The population was 10,842 at the 2000 census. It is named for Erastus Corning, an Albany financier and railroad executive who was an investor in the company that developed the community.- Overview :The city of...

 by the confluence of the Tioga River

Tioga River (Chemung River)

The Tioga River is a tributary of the Chemung River, approximately long, in northern Pennsylvania and western New York in the United States...

 and Cohocton

Cohocton River

The Cohocton River is a tributary of the Chemung River in western New York in the United States. Via the Chemung River, it is part of the Susquehanna River watershed, flowing to Chesapeake Bay...

 rivers.