LaSalle County, IL: flood risk, in FEMA's own numbers
On FEMA's National Risk Index, LaSalle County scores at the 88.2th percentile for flood hazard, rated "Relatively Moderate" — a middling flood hazard by national standards. The hazard here is driven by inland rivers and flash flooding rather than the coast — FEMA's model puts a flood event here at about 2 times a year. This describes the county, not any one street — FEMA only publishes exact parcel zones through a live map service.
Who actually carries the flood insurance FEMA requires
Homes with a federally backed mortgage inside LaSalle 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, 20.2% of them do — 135 active policies against 668 structures FEMA counts in that zone, leaving a real compliance gap. Looking beyond the mandated zone, 0.5% of all residential structures in LaSalle County carry flood coverage voluntarily or otherwise — relevant because most NFIP claims nationally come from outside the mapped SFHA.
How LaSalle County compares nationally
Among the 3144 US counties FEMA scores for flood hazard, LaSalle County ranks 390 — 1 being the highest hazard nationally — and 584 by population among all 3144 counties covered here, where 1 is the largest. LaSalle County, Illinois is home to about 108,390 people across 1,135.117 square miles of land.
Your street may differ from LaSalle County's average
FEMA counts 41,450 residential structures in LaSalle County overall, 222 of them carrying some form of NFIP coverage — but a lender or insurer cares about one parcel, not that county total.
Where LaSalle 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.