Sixty-two percent of the American population lives in counties with levees. A decade ago, the percentage was 55%.
Levees.org filed a request under FOIA for the data on May 12, 2019 and just received it on July 29, 2020, over fourteen months later.
According to FEMA, the increase is likely due to several factors, including expansion of existing levees and construction of new levees; more people moving to locations protected by levees; and a better accounting of where flood-risk-reduction levees are located.
Levees.org offered this data and its statistic results to the The Advocate. Reporters Mark Schleifstein and Jeff Adelson have done a good story. See it here.