On July 26, Brandon Jones’s St. Louis home was hit by major flooding for the second time since 2008, when he moved in. Cars were barely visible under several feet of turgid storm water, as record rainfall fell on the city.

‘Oh, my God,’ Jones said in a video he posted to Facebook. ‘I’m stuck and can’t even go nowhere.’ Two days later, the area flooded all over again.

But Jones’s Penrose neighborhood isn’t designated as a high-risk location on the Federal Emergency Management Agency’s flood maps. These high-risk zones, which lie in what’s called the Special Flood Hazard Area (SFHA), cover properties that the agency considers to have at least a 1 percent annual chance of flooding.

This 100-year flood plain designation requires property owners with federally backed mortgages to buy flood insurance, and it influences how communities regulate development.

A Washington Post investigation uncovered communities throughout the country where FEMA’s maps are failing to warn Americans about flood risk. As climate change accelerates, it is increasing types of flooding that the maps aren’t built to include.