How much flood risk does Aiken County actually carry?
Aiken County lands at the 84.4th percentile of FEMA's National Risk Index for flooding, "Relatively Moderate" territory — a middling flood hazard by national standards — with the hazard driven by inland rivers and flash flooding rather than the coast — FEMA's model puts a flood event here at about once every 2 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 Aiken County
46.7% of the homes FEMA requires to carry flood insurance in Aiken County — those inside the mapped Special Flood Hazard Area — actually have a policy in force: 328 policies against 702 mandated structures, which means a meaningful share of legally-required coverage simply isn't there. Across all residential structures in Aiken County, not just the ones FEMA mandates, 0.6% carry an NFIP policy — most flood damage nationally happens outside the mapped high-risk zone, so that broader number matters too.
Where Aiken County ranks
Aiken County sits at rank 512 of 3144 counties on FEMA's flood hazard scale (1 is worst) and rank 389 of 3144 by population (1 is biggest). About 179,245 people live in Aiken County, South Carolina, spread over 1,070.676 square miles.
Checking a specific address in Aiken County
Across all of Aiken County's 80,358 residential structures, 486 carry an NFIP policy today — a county-wide count that still can't tell you one address's own mapped zone.
More on how this number was built
The methodology guide shows exactly which FEMA and Census tables feed Aiken 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.