Is New Castle County, DE in a flood zone?
FEMA's National Risk Index puts New Castle County's flood hazard at the 97.6th percentile nationally — well above the national norm for flood hazard — driven by inland rivers and flash flooding rather than the coast — FEMA's model puts a flood event here at about 6.6 times a year. This describes the county, not any one street — FEMA only publishes exact parcel zones through a live map service.
New Castle County's flood-insurance compliance gap
44.5% of the homes FEMA requires to carry flood insurance in New Castle County — those inside the mapped Special Flood Hazard Area — actually have a policy in force: 893 policies against 2,006 mandated structures, which means a meaningful share of legally-required coverage simply isn't there. Across all residential structures in New Castle County, not just the ones FEMA mandates, 0.9% carry an NFIP policy — most flood damage nationally happens outside the mapped high-risk zone, so that broader number matters too.
How New Castle County compares nationally
New Castle County sits at rank 86 of 3144 counties on FEMA's flood hazard scale (1 is worst) and rank 121 of 3144 by population (1 is biggest). About 588,093 people live in New Castle County, Delaware, spread over 426.338 square miles.
What to do next if you own or are buying in New Castle County
FEMA counts 181,854 residential structures in New Castle County overall, 1,599 of them carrying some form of NFIP coverage — but a lender or insurer cares about one parcel, not that county total.
More on how this number was built
The methodology guide shows exactly which FEMA and Census tables feed New Castle 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.