How much flood risk does Carbon County actually carry?
Carbon County lands at the 72.3th percentile of FEMA's National Risk Index for flooding, "Relatively Low" territory — below the national norm for flood hazard — with the hazard driven by inland rivers and flash flooding rather than the coast — FEMA's model puts a flood event here at about once every 2 years. 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 Carbon 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, 6.4% of them do — 39 active policies against 613 structures FEMA counts in that zone, leaving a real compliance gap. Across all residential structures in Carbon County, not just the ones FEMA mandates, 0.8% carry an NFIP policy — most flood damage nationally happens outside the mapped high-risk zone, so that broader number matters too.
Where Carbon County ranks
Carbon County sits at rank 911 of 3144 counties on FEMA's flood hazard scale (1 is worst) and rank 2318 of 3144 by population (1 is biggest). About 11,498 people live in Carbon County, Montana, spread over 2,047.889 square miles.
Checking a specific address in Carbon County
65 of Carbon County's 7,890 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 Carbon 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.