Is Rock Island County, IL in a flood zone?
FEMA's National Risk Index puts Rock Island County's flood hazard at the 79.5th percentile nationally — a middling flood hazard by national standards — driven by inland rivers and flash flooding rather than the coast — FEMA's model puts a flood event here at about 3.1 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.
Rock Island County's flood-insurance compliance gap
23.7% of the homes FEMA requires to carry flood insurance in Rock Island County — those inside the mapped Special Flood Hazard Area — actually have a policy in force: 613 policies against 2,585 mandated structures, which means a meaningful share of legally-required coverage simply isn't there. Across all residential structures in Rock Island County, not just the ones FEMA mandates, 1.3% carry an NFIP policy — most flood damage nationally happens outside the mapped high-risk zone, so that broader number matters too.
Where Rock Island County ranks
Rock Island County sits at rank 673 of 3144 counties on FEMA's flood hazard scale (1 is worst) and rank 476 of 3144 by population (1 is biggest). Rock Island County, Illinois covers 427.497 square miles and counts roughly 142,731 residents.
Checking a specific address in Rock Island County
668 of Rock Island County's 52,629 residential structures carry flood coverage of some kind, per FEMA's latest count — useful context, not a substitute for checking one parcel.
More on how this number was built
The methodology guide shows exactly which FEMA and Census tables feed Rock Island County's numbers. The guide to what the Special Flood Hazard Area actually means explains why the mandatory-insurance rule exists and who it applies to.