Tracking Old Maps As They Are Phased Out
FEMA starting using its current mapping technology in the early 2000's.
The maps from before the early 2000's going back to the 1970s are still valid, but are not easy to access.
National Flood Data has converted all of these to a modern format so that they can be integrated into our services.
There are over 3,000 counties in the United States, and FEMA updates about 60 to 75 county maps every month.
Most updates are for maps that are already in the modern format, but most months several of the older maps from earlier than 2000 are replaced.
National Flood Data tracks all of these updates and replaces the older map with the new map.
Occasionally only part of a county gets a new map and the old map still applies in the rest of the county.
In these cases National Flood Data makes the appropriate update and reconciles the old and the new maps.
Map of counties with valid older maps as of December 2020.