Marion County, IL flood risk explained
Flood hazard in Marion County sits at the 68.1th national percentile, below 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 1.1 times a year. County-wide, not parcel-specific: FEMA's real flood-zone map is queried live, never shipped as a download.
Mandatory flood insurance compliance in Marion County
Homes with a federally backed mortgage inside Marion County's mapped high-risk flood zone (the Special Flood Hazard Area, or SFHA) are legally required to carry an NFIP flood policy. In practice, 8.8% of them do — 15 active policies against 170 structures FEMA counts in that zone, leaving a real compliance gap. Looking beyond the mandated zone, 0.1% of all residential structures in Marion County carry flood coverage voluntarily or otherwise — relevant because most NFIP claims nationally come from outside the mapped SFHA.
Where Marion County ranks
Among the 3144 US counties FEMA scores for flood hazard, Marion County ranks 1046 — 1 being the highest hazard nationally — and 1284 by population among all 3144 counties covered here, where 1 is the largest. Marion County, Illinois is home to about 36,437 people across 572.538 square miles of land.
Checking a specific address in Marion County
FEMA counts 15,888 residential structures in Marion County overall, 18 of them carrying some form of NFIP coverage — but a lender or insurer cares about one parcel, not that county total.
Where Marion 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.