About the Data

DisasterAtlasUSA is built from federal records: OpenFEMA disaster declarations and assistance programs, NOAA Storm Events, USGS earthquake history, and wildfire datasets from NIFC. U.S. Census Bureau geography and population are used to place events and, where useful, normalize frequencies.

A unified event record

Each source describes events differently. We reduce them to one shape — type, date, place, scale — so a county page can show every kind of event on one timeline. Federal disaster declarations in the FEMA record go back to 1953.

History is not a forecast

A count of past events tells you what has happened, not what will. We phrase everything as "since 1980, FEMA issued N declarations for this county", never as "it is dangerous to live here". For current threats, the authoritative sources are the National Weather Service and FEMA directly, and we link to them rather than substitute for them.

Aid is not damages

Assistance figures are how much federal money was obligated under a program. They are not an estimate of total economic loss, which is usually far larger and measured separately.

How current it is

The federal archives are refreshed on a regular schedule, so recent declarations and storm events appear here within days to weeks of being published.