Harris County, TX flood risk explained
Flood hazard in Harris County sits at the 100th national percentile, among the highest 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 5.1 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.
Who actually carries the flood insurance FEMA requires
Homes with a federally backed mortgage inside Harris 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, 48.4% of them do — 54,764 active policies against 113,215 structures FEMA counts in that zone, leaving a real compliance gap. Looking beyond the mandated zone, 16.6% of all residential structures in Harris County carry flood coverage voluntarily or otherwise — relevant because most NFIP claims nationally come from outside the mapped SFHA.
Harris County against the rest of the country
Among the 3144 US counties FEMA scores for flood hazard, Harris County ranks 2 — 1 being the highest hazard nationally — and 3 by population among all 3144 counties covered here, where 1 is the largest. Harris County, Texas is home to about 5,009,302 people across 1,707.103 square miles of land.
Your street may differ from Harris County's average
FEMA counts 1,245,880 residential structures in Harris County overall, 206,279 of them carrying some form of NFIP coverage — but a lender or insurer cares about one parcel, not that county total.
Where Harris 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.