One-quarter of U.S. critical infrastructure at risk of failure due to flooding

About 25% of all critical infrastructure in the U.S. is at risk of failure due to flooding, according to a new report by the First Street Foundation, a nonprofit research and technology group.

Nearly 2 million miles of road—roughly 23% of US roadways—are at risk of becoming impassable due to flooding, the report also found. Researchers examined five categories of infrastructure in the contiguous U.S., including the District of Columbia: Critical infrastructure; social infrastructure, including museums, government buildings and schools; roads; commercial properties; and residential properties.

Researchers examined estimates of operational flood risk from government agencies to determine the amount of flooding it would take to knock different types of facilities or services offline. They then overlaid the kinds of flood events that can be expected in an area at least once every two years.

Louisiana is home to six of the top 20 most at-risk counties in the country, making it the most vulnerable state. Though many coastal areas in other states are threatened, flood risk is also a threat in inland states. Areas such as McDowell County in West Virginia and Johnson County in Kentucky are among the most at-risk because of the growing threat of heavy rain.