Susquehanna River
Longest river on the East Coast, feeding half of Chesapeake Bay
Some geologists count the Susquehanna among the oldest rivers on Earth, with estimates reaching back roughly 300 million years, and its path slices straight through ridge after ridge of the Appalachians in a series of water gaps. At 444 miles (715 km) it is the longest river on the East Coast of the United States. It leaves Otsego Lake at Cooperstown, New York, loops through Pennsylvania, gathers its West Branch at Northumberland and empties into the head of Chesapeake Bay at Havre de Grace, Maryland.
Half of the freshwater flowing into Chesapeake Bay comes from the Susquehanna, so the health of the bay depends on what happens across its 27,500-square-mile (71,000 km²) basin. The river is wide but shallow and rocky, and even today no commercial boats travel it. The name probably comes from a Lenape word often translated as muddy river. Harrisburg, Pennsylvania's capital, stands on its east bank near the 1902 Rockville Bridge, the longest stone masonry arch bridge in the world. Downstream lie Three Mile Island, site of the 1979 nuclear accident, and Conowingo Dam.