Flooding is the most common natural disaster in Pennsylvania. Pennsylvania has access to the Ohio, Delaware, and Susquehanna Rivers. These major rivers draw their water from countless smaller rivers and streams; in fact, Pennsylvania has more miles of waterways than roadways. With Pennsylvania's climate and topography, water is very commonly available and few places are more than a few miles from the nearest stream. Even though this map only references about a dozen major flood events that have had devastating consequences, there have been many other significant floods less impactful. Smaller floods happen yearly and can have similarly dire consequences for smaller numbers of residents.
Many major floods have impacted areas of Pennsylvania and changed the way we looked at dealing with this type of natural disaster. These floods can cause critical damage to homes, infrastructure, and property. By understanding which areas of the states are most prone to flooding and what meteorological conditions lead to floods, we can focus on mitigating the threats in these parts of the state first. Doing so can create a safer community and potentially decrease the amount of lives lost to these deadly disasters. This has been the strategy taken by state and federal agencies since the early 1900s.
| Flood | Year | Death Total in PA | Damages in Current (then) $ | Damages in 2023 $ |
|---|---|---|---|---|
| Johnstown | 1889 | 2,209 | $17 million | $557 million |
| St. Patrick's Day | 1936 | 69 | $300 million | $6 billion |
| Hurricane Diane | 1955 | 101 | $70 million | $788 million |
| Hurricane Agnes | 1972 | 50 | $2 billion | $14 billion |
| Hurricane Eloise | 1975 | 17 | $200 million | $1.5 billion |
| Johnstown | 1977 | 84 | $340 million | $1.6 billion |
| Hurricane Irene | 2011 | 6 | $425 million | $570 million |