Large shares of the U.S. population live in the parts of the country most vulnerable to major disasters, mainly coastal areas prone to hurricane damage. Hurricanes Katrina, Sandy, Harvey and Irma all hit heavily populated coasts.
Seven of the 10 largest metropolitan areas in the U.S. are on or near the coast, accounting for more than 60 million people. In fact, the vast majority of counties with more than 500,000 inhabitants are concentrated on the coast.
More than 5 million Americans also live on islands like Puerto Rico and Hawaii, where a hurricane, volcanic eruption or tsunami can be devastating.
California has been spared landfall of a major tropical cyclone, but torrential rainfall still causes severe damage along the coast. On top of this, most of California’s coastal cities are adjacent to the San Andreas Fault, which caused the death of around 3,000 people in 1906. Geologists agree that another large earthquake is bound to occur.
Large concentrations of people pose problems, too. To support large populations in small spaces, cities need advanced large-scale infrastructure – not only to house people, but to deliver utilities like electricity and gas, as well as to tame water with dams, levies and spillways.
While such infrastructure is impressive, its occasional failure can have grave consequences. In several of the most severe American disasters, infrastructure collapse caused substantial damage. In New Orleans, the Lower Ninth Ward was violently flooded when levies collapsed. In the 1906 San Francisco earthquake disaster, gas mains ruptured, fueling a deadly fire that tore through the city for days.
The large cities on the coasts are consistently growing larger. The 10 largest metropolitan areas on the coast alone have grown by almost 5 million people since 2010, an increase of nearly 7 percent.
Experts project that by 2040, these 10 metropolitan areas will add a whopping 16.7 million more people, making the total population around 92.5 million people – most of whom will be particularly vulnerable to disaster.