The Bureau of Economic and Business Research at the University of Florida found that every Keys city and the unincorporated areas of Monroe County lost residents between 2017 and 2018.
The survey found the overall population in the Keys dropped to 73,940 - a loss of nearly 3,000 people.
Irma hit the Keys with storm surge and 130-mph (210-kph) winds in September 2017, destroying thousands of homes.
The Citizen reports the annual survey is conducted using U.S. Census data and ratios of utility bills.
Monroe County Superintendent Mark Porter said schools in the Keys lost about 140 students. Porter said he worried rising housing costs would exacerbate the decline.
Information from: The Key West (Fla.) Citizen, http://www.keysnews.com
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