Hurricane Agnes still ranks as Pa.'s worst disaster
http://www.usatoday.com/weather/hurricane/2002/6-20-agnes-revisited.htm
Agnes was before my time.
I remember that one. It packed quite a wallop quite far inland.
We were supposed to visit Sunbury, PA the day after the storm came through. Sunbury is the only town along the Susquehanna which didn't flood, because it had a rather large flood wall. They also had the world's largest Fabricated Dam, but the hurricane wiped out the million-dollar marina they had installed above it.
Needless to say, we didn't go, because the city was closed (flood gates shut).
Trivia: They were debating pulling down the walls, because they people along the river thought they were ugly, and they hadn't had flood since they started building it.