Cook County, IL: flood risk, in FEMA's own numbers
On FEMA's National Risk Index, Cook County scores at the 99.9th percentile for flood hazard, rated "Very High" — among the highest flood hazard in the country. 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 5.9 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.
Mandatory flood insurance compliance in Cook County
32% of the homes FEMA requires to carry flood insurance in Cook County — those inside the mapped Special Flood Hazard Area — actually have a policy in force: 4,016 policies against 12,558 mandated structures, which means a meaningful share of legally-required coverage simply isn't there. Looking beyond the mandated zone, 0.5% of all residential structures in Cook County carry flood coverage voluntarily or otherwise — relevant because most NFIP claims nationally come from outside the mapped SFHA.
Where Cook County ranks
Among the 3144 US counties FEMA scores for flood hazard, Cook County ranks 4 — 1 being the highest hazard nationally — and 2 by population among all 3144 counties covered here, where 1 is the largest. Cook County, Illinois is home to about 5,182,617 people across 944.93 square miles of land.
Your street may differ from Cook County's average
6,353 of Cook County's 1,241,949 residential structures carry flood coverage of some kind, per FEMA's latest count — useful context, not a substitute for checking one parcel.
Where Cook 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.