King County, WA flood risk explained
Flood hazard in King County sits at the 99.5th national percentile, among the highest flood hazard in the country; driven by inland rivers and flash flooding rather than the coast — FEMA's model puts a flood event here at about once every 4 years. This describes the county, not any one street — FEMA only publishes exact parcel zones through a live map service.
Mandatory flood insurance compliance in King County
44.1% of the homes FEMA requires to carry flood insurance in King County — those inside the mapped Special Flood Hazard Area — actually have a policy in force: 2,558 policies against 5,797 mandated structures, which means a meaningful share of legally-required coverage simply isn't there. Looking beyond the mandated zone, 0.8% of all residential structures in King County carry flood coverage voluntarily or otherwise — relevant because most NFIP claims nationally come from outside the mapped SFHA.
King County against the rest of the country
Among the 3144 US counties FEMA scores for flood hazard, King County ranks 18 — 1 being the highest hazard nationally — and 12 by population among all 3144 counties covered here, where 1 is the largest. King County, Washington is home to about 2,340,211 people across 2,115.75 square miles of land.
Your street may differ from King County's average
Across all of King County's 578,363 residential structures, 4,529 carry an NFIP policy today — a county-wide count that still can't tell you one address's own mapped zone.
Where King 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.