Mercer County, OH: flood risk, in FEMA's own numbers
On FEMA's National Risk Index, Mercer County scores at the 42.1th percentile for flood hazard, rated "Relatively Low" — below the national norm for flood hazard. 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 2.3 times a year. This describes the county, not any one street — FEMA only publishes exact parcel zones through a live map service.
Mercer County's flood-insurance compliance gap
Out of 299 homes FEMA counts inside Mercer County's mapped flood zone, 32 carry the flood policy federal law requires there — 10.7% compliance, short of full coverage. Looking beyond the mandated zone, 0.4% 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.
Mercer County against the rest of the country
Among the 3144 US counties FEMA scores for flood hazard, Mercer County ranks 1881 — 1 being the highest hazard nationally — and 1137 by population among all 3144 counties covered here, where 1 is the largest. Mercer County, Ohio covers 462.447 square miles and counts roughly 42,648 residents.
Checking a specific address in Mercer County
Across all of Mercer County's 15,961 residential structures, 56 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.