The Susquehanna River is a major river located in Mid-Atlantic region of the United States, overlapping between the lower Northeast and the Upland South. At 444 miles 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.
The Susquehanna River forms from two main branches: the North Branch, which rises in Cooperstown, New York, and is regarded by federal mapmakers as the main branch or headwaters, and the West Branch, which rises in western Pennsylvania and joins the main branch near Northumberland in central Pennsylvania.
The river drains 27,500 square miles, including nearly half of the land area of Pennsylvania. The drainage basin includes portions of the Allegheny Plateau region of the Appalachian Mountains, cutting through a succession of water gaps in a broad zigzag course to flow across the rural heartland of southeastern Pennsylvania and northeastern Maryland in the lateral near-parallel array of mountain ridges.