By State › Pennsylvania

Pennsylvania: Risks & Trends

Download all of Pennsylvania as PDF Print

Same standard as every other page on this site: every figure below is independently sourced, and figures that vary across sources, or measure genuinely different things, are flagged as such rather than collapsed into one number that looks more precise than the underlying data actually supports.

Hurricane Agnes (1972): the worst disaster in Pennsylvania’s recorded history

MetricFigure
Pennsylvania deaths 50
Pennsylvania damage (1972 dollars) $2.3 billion
People evacuated statewide 100,000+
People left homeless statewide 220,000+
Homes and businesses damaged or destroyed 68,000 homes / 3,000+ businesses
U.S.-wide deaths (for comparison) 119

Why Pennsylvania's share of this disaster was so disproportionate

Agnes made its actual landfall on the Florida Panhandle and had weakened to a tropical depression by the time it reached Pennsylvania, but it stalled over the state’s river basins for days, dumping enormous rainfall on already-saturated ground. Pennsylvania’s share of the storm’s total U.S. damage was larger than every other affected state combined; then-Governor Milton Shapp called it, without qualification, the worst disaster in Pennsylvania’s history. The lesson isn’t about hurricane category or landfall strength, it’s about a weakened system’s rainfall meeting a river basin’s terrain.

Hurricane Ida remnants (2021): the same mechanism, half a century later

MetricFigure
Pennsylvania deaths 5+
Rainfall, eastern/south-central PA 5-10 in, most within about 6 hours
Schuylkill River crest in Philadelphia Highest level in more than 150 years
Pennsylvania damage estimate $117 million+

Ida’s Pennsylvania toll was far smaller than Agnes’s in absolute terms, but the mechanism was identical: a tropical system, by then a post-tropical remnant, dropped its rainfall over a short window directly onto a Pennsylvania river basin, and the Schuylkill responded by rising to a height the city hadn’t seen in a century and a half.

What these two have in common

Separated by 49 years, Agnes and Ida demonstrate the same structural risk: Pennsylvania doesn’t need a hurricane to make landfall on its own soil to suffer a landmark flood disaster, it only needs a weakening tropical system to stall its rain over the right river basin. That’s a very different risk profile from every coastal state covered on this site, and it means hurricane season matters in Pennsylvania even though no hurricane has ever technically made landfall there.

Sources