According to climate researcher Ben Strauss, Florida, Louisiana, California and New York are the states most vulnerable to flooding. A 2013 report ranked Miami; New York; New Orleans; Tampa, Florida; and St. Petersburg, Florida as the most flood-prone cities in the United States. Most of Florida is especially vulnerable to floods, because the state's largest cities are concentrated along the coast. Over 1.6 million people in Florida live less than a meter above sea level.
Miami often floods at high tide even when the city doesn't experience storms, and researchers expect the situation to get worse over time. Local authorities in Florida have few solutions available since the land is not strong enough to support building a seawall.
Louisiana experienced devastating flooding because of Hurricane Katrina in 2005, and over 880,000 people in the state live less than a meter above sea level. California faces flood risks because many people in this state live in heavily populated coastal cities, such as Long Beach. New York authorities feared that Manhattan would flood during Hurricane Irene, but the island escaped major damage because of seawalls. Beach neighborhoods on Long Island were devastated, however.
Flood risk is not limited to coastal states. Areas along rivers in Midwestern states such as Minnesota, North Dakota and Missouri have historically experienced heavy flood damage.