The Susquehanna River is one of the oldest existing rivers in the world. It is also the longest river in the Eastern U.S. at 464 miles. It begins at Otsego Lake in NY and drains into the Chesapeake Bay in MD, with a western branch extending through central Pennsylvania. The river has played significant role throughout the history of America, including the importance to the Len'api peoples (reflected in many of the place-names), important events in the Revolutionary War, the Industrial Revolution, the Civil War and of course the meltdown at Three Mile Island. Railroads eventually supplanted the river as a transportation venue and many of the canals have been filled in. But 200 bridges and one operating ferry still cross the river, which is now used more for recreation.