Mercer County, PA: flood risk, in FEMA's own numbers
On FEMA's National Risk Index, Mercer County scores at the 87.9th percentile for flood hazard, rated "Relatively Moderate" — a middling flood hazard by national standards. The hazard here is driven by inland rivers and flash flooding rather than the coast — FEMA's model puts a flood event here at about 2.5 times a year. That's a county-wide figure, not a per-address one — FEMA's parcel maps are a live lookup, not a bulk file.
Who actually carries the flood insurance FEMA requires
Out of 484 homes FEMA counts inside Mercer County's mapped flood zone, 42 carry the flood policy federal law requires there — 8.7% compliance, short of full coverage. Looking beyond the mandated zone, 0.1% of all residential structures in Mercer County carry flood coverage voluntarily or otherwise — relevant because most NFIP claims nationally come from outside the mapped SFHA.
How Mercer County compares nationally
Among the 3144 US counties FEMA scores for flood hazard, Mercer County ranks 400 — 1 being the highest hazard nationally — and 585 by population among all 3144 counties covered here, where 1 is the largest. Mercer County, Pennsylvania is home to about 108,140 people across 672.538 square miles of land.
What to do next if you own or are buying in Mercer County
Across all of Mercer County's 49,504 residential structures, 62 carry an NFIP policy today — a county-wide count that still can't tell you one address's own mapped zone.
Where Mercer 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.