How much flood risk does Jefferson County actually carry?
Jefferson County lands at the 91.3th 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 3.1 times a year. County-wide, not parcel-specific: FEMA's real flood-zone map is queried live, never shipped as a download.
Mandatory flood insurance compliance in Jefferson County
Jefferson County is one of the counties where FEMA's own denominator for mandated flood-zone structures is missing, so no compliance rate is shown rather than a guessed one — the data quality guide covers how common this is. Across all residential structures in Jefferson County, not just the ones FEMA mandates, 22% carry an NFIP policy — most flood damage nationally happens outside the mapped high-risk zone, so that broader number matters too.
Jefferson County against the rest of the country
Jefferson County sits at rank 292 of 3144 counties on FEMA's flood hazard scale (1 is worst) and rank 290 of 3144 by population (1 is biggest). Jefferson County, Texas is home to about 253,948 people across 876.736 square miles of land.
Your street may differ from Jefferson County's average
18,645 of Jefferson County's 84,841 residential structures carry flood coverage of some kind, per FEMA's latest count — useful context, not a substitute for checking one parcel.
More on how this number was built
The methodology guide shows exactly which FEMA and Census tables feed Jefferson County's numbers. See the data quality guide for why Jefferson County, like hundreds of other counties, doesn't get a clean compliance percentage.