These Floridians rebuilt houses in flood zones. Now FEMA is cracking down.

Enforcement of the 50 percent rule largely falls to local officials in flood-damaged regions, who are charged with ensuring that their constituents aren’t rebuilding in flood zones. In exchange for this diligence, the federal government subsidizes low-cost flood insurance for homes in communities that certify their compliance with the rule, goosing red hot real estate markets in Florida and other scenic but climate-threatened regions.