Corson County, SD flood risk explained
Flood hazard in Corson County sits at the 16.1th national percentile, among the lowest 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 1.7 times a year. This describes the county, not any one street — FEMA only publishes exact parcel zones through a live map service.
Corson County's flood-insurance compliance gap
Homes with a federally backed mortgage inside Corson 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, 0% of them do — 0 active policies against 35 structures FEMA counts in that zone, leaving a real compliance gap. Looking beyond the mandated zone, 0% of all residential structures in Corson County carry flood coverage voluntarily or otherwise — relevant because most NFIP claims nationally come from outside the mapped SFHA.
How Corson County compares nationally
Among the 3144 US counties FEMA scores for flood hazard, Corson County ranks 2671 — 1 being the highest hazard nationally — and 2902 by population among all 3144 counties covered here, where 1 is the largest. Corson County, South Dakota is home to about 3,747 people across 2,469.694 square miles of land.
What to do next if you own or are buying in Corson County
1 of Corson County's 2,357 residential structures carry flood coverage of some kind, per FEMA's latest count — useful context, not a substitute for checking one parcel.
Where Corson 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.