Is Lewis County, MO in a flood zone?
FEMA's National Risk Index puts Lewis County's flood hazard at the 37.1th percentile nationally — below 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 1.5 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 Lewis County
Homes with a federally backed mortgage inside Lewis 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, 5.1% of them do — 5 active policies against 98 structures FEMA counts in that zone, leaving a real compliance gap. Across all residential structures in Lewis County, not just the ones FEMA mandates, 0.5% carry an NFIP policy — most flood damage nationally happens outside the mapped high-risk zone, so that broader number matters too.
Lewis County against the rest of the country
Lewis County sits at rank 2043 of 3144 counties on FEMA's flood hazard scale (1 is worst) and rank 2419 of 3144 by population (1 is biggest). Lewis County, Missouri is home to about 9,852 people across 505.018 square miles of land.
Your street may differ from Lewis County's average
FEMA counts 5,519 residential structures in Lewis County overall, 27 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 Lewis 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.