Susquehanna, a river of America, formed by the junction at Northumberland, Pennsylvania, of the North Branch (350 m.) flowing out of Schuyler Lake, central New York, and the West Branch (250 m.) rising in the Alleghany Mountains; flows in a shallow, rapid, unnavigable course S. and SE. through beautiful scenery to Port Deposit, at the N. end of Chesapeake Bay; length, 150 m.