1. Locate the address
A server-side GET request uses the Census current address-range benchmark and current geographic vintage. The returned coordinate is commonly interpolated along a street segment. Review the matched address before querying FEMA. The point may fall on a road or away from the building.
2. Query the effective flood layer
The app discovers FEMA’s Flood Hazard Zones and FIRM Panels layers from service metadata instead of assuming numeric layer IDs. It sends a WGS84 point-intersection query and displays FEMA’s FLD_ZONE, ZONE_SUBTY, SFHA_TF and available elevation or depth attributes. A missing feature never becomes Zone X. Overlapping features are flagged.
3. Check panels and letters
The panel query returns the FIRM panel identifier and effective date. A LOMA layer, when discovered, is checked for point intersection. No point intersection does not prove that no letter applies to the property. Preliminary maps, missing digital coverage and building boundary cases require official review.
4. Aggregate the published NFIP report
Policy and loss geography data are from the complete August 31, 2026 HUDEX workbook. Community rows are summed by the report’s geocoded county FIPS. State totals preserve records without an assigned county. Policy Count includes condominium units under master policies. Average annual premium plus federal policy fee is the report’s Total Premium + FPF divided by Policy Count, per policy unit. This is not a quote or an average for an individual building type.
5. Read losses and rated zone groups
Cumulative loss counts include losses closed without payment. Net dollars paid follow the source’s published adjustments. The geography workbook does not specify a first loss year or annual breakdown; the site does not infer either. The separate zone workbook supplies grouped policy statistics. Group averages are not individual AE or shaded-X averages. Zone-workbook loss totals differ from HUDEX; the two loss populations are not mixed.
6. Geography and refresh
Counties and internal points use the 2025 Census Gazetteer. City launch pages use the 300 largest incorporated places with matched 2024 population estimates, Gazetteer points and the Census place-to-county list. Cities spanning several counties explicitly identify the county whose statistics are shown. Cache lifetimes: map responses 24 hours, address matches 30 days. The rounded-coordinate cache key also includes the exact coordinate hash, preventing nearby addresses from sharing a different point’s zone.
Annual claims history
A complete keyset-paginated extraction of 2,725,989 OpenFEMA NFIP claims V3 records provides annual net payments by reported county and year of loss. The September 8, 2026 source release includes 62,433 records without a usable county; those are retained in national controls and not assigned to counties. Payments sum net building, contents and increased-cost-of-compliance amounts. The annual series is a separate population from the August 31 HUDEX totals. Historical dollars are nominal.