Chester County, PA flood risk explained
Flood hazard in Chester County sits at the 94.3th national percentile, well above the national norm for flood hazard; driven by inland rivers and flash flooding rather than the coast — FEMA's model puts a flood event here at about 5.5 times a year. This describes the county, not any one street — FEMA only publishes exact parcel zones through a live map service.
Chester County's flood-insurance compliance gap
39.8% of the homes FEMA requires to carry flood insurance in Chester County — those inside the mapped Special Flood Hazard Area — actually have a policy in force: 509 policies against 1,279 mandated structures, which means a meaningful share of legally-required coverage simply isn't there. Looking beyond the mandated zone, 0.6% of all residential structures in Chester County carry flood coverage voluntarily or otherwise — relevant because most NFIP claims nationally come from outside the mapped SFHA.
How Chester County compares nationally
Among the 3144 US counties FEMA scores for flood hazard, Chester County ranks 196 — 1 being the highest hazard nationally — and 128 by population among all 3144 counties covered here, where 1 is the largest. Chester County, Pennsylvania is home to about 560,745 people across 750.553 square miles of land.
Checking a specific address in Chester County
FEMA counts 159,896 residential structures in Chester County overall, 1,015 of them carrying some form of NFIP coverage — but a lender or insurer cares about one parcel, not that county total.
Where Chester County's figures come from
Every figure on this page traces to a named FEMA dataset, documented in the methodology guide. If you're unsure why any of this insurance requirement exists at all, the SFHA explainer covers it from first principles.