Introducing FloodzoneData.us, presenting data on the people and housing in the U.S. floodplain

FloodzoneData.us is a new data tool presented by the NYU Furman Center describing the people and housing located in the nation’s floodplains. The interactive map and data downloads make information available at the state, county, and Census tract levels. As sea levels rise and storms intensify due to climate change, FloodzoneData.us is a resource to help policymakers and communities plan for the effects of flooding.

The NYU Furman Center’s FloodzoneData.us combines housing and population data with FEMA maps of the 100-year floodplain (the term for areas with a one percent probability of flooding each year) and the 500-year floodplain (areas with a 0.2 percent probability of flooding each year).

According to a new analysis released in conjunction with FloodzoneData.us, Florida, Texas, and California have the largest numbers of housing units in the 100-year floodplain. In Florida, nearly two million occupied housing units are located in the 100-year floodplain; Texas has about 612,000 housing units and California has about 388,000 units in the 100-year floodplain.

The NYU Furman Center also found that the majority of the housing units in the combined 100- and 500-year U.S. floodplains are single-family homes (64%) and are owner-occupied (62%).

The age of housing units in the U.S. floodplain, and thus how likely they are to be compliant with flood-resistant construction standards, varies widely; 22% of units in the 100-year floodplain were built before 1960 and therefore are less likely to be built to standards created with FEMA’s 1968 National Flood Insurance Program. Units built after 2000, which are more likely to be compliant, account for the smallest share (19%) of housing in the 100-year floodplains.

A large share of all U.S. public housing units (9%) are located in the combined 100- and 500-year floodplains. In addition, 8% of all privately-owned subsidized rental housing units in the U.S. are located in the combined 100- and 500-year floodplains.