How much flood risk does Northumberland County actually carry?
Northumberland County lands at the 88.3th 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 1.3 times a year. County-wide, not parcel-specific: FEMA's real flood-zone map is queried live, never shipped as a download.
Who actually carries the flood insurance FEMA requires
Homes with a federally backed mortgage inside Northumberland 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, 15.3% of them do — 258 active policies against 1,692 structures FEMA counts in that zone, leaving a real compliance gap. Across all residential structures in Northumberland County, not just the ones FEMA mandates, 1% carry an NFIP policy — most flood damage nationally happens outside the mapped high-risk zone, so that broader number matters too.
How Northumberland County compares nationally
Northumberland County sits at rank 386 of 3144 counties on FEMA's flood hazard scale (1 is worst) and rank 669 of 3144 by population (1 is biggest). About 90,027 people live in Northumberland County, Pennsylvania, spread over 457.678 square miles.
Checking a specific address in Northumberland County
Across all of Northumberland County's 35,495 residential structures, 365 carry an NFIP policy today — a county-wide count that still can't tell you one address's own mapped zone.
More on how this number was built
The methodology guide shows exactly which FEMA and Census tables feed Northumberland 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.