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Rising sea levels. Runoff from rapidly melting snow and ice. Rivers and streams overflowing their banks. As climate change continues to wreak havoc on the environmental norms humans widely take for granted, the frequency and severity of extreme weather has increased on a global scale. Floods, the most common and fatal natural disasters in the U.S., continue to get more destructive. Catastrophic flooding events once thought to occur every 100 years . And the are projected to grow by roughly 45% by the end of the century.

Because of the deterioration and fragility of historical buildings, as well as long-term degradation of the natural environment around these structures, historic sites are often at serious risk of flooding. identified historic buildings of national significance across the U.S. located in census tracts with very or relatively high risk of flooding, using data from and the. The National Park Service outlines for what makes a historic building on the registry nationally significant, a less rigorous designation than being considered a National Historic Landmark. FEMA calculated the risk of flooding for each census tract by combining geospatial and historic flood-event data from the and . For each state, a maximum of three historic sites are listed in order of their flood risk, though many states have more at-risk sites in total. Colorado, Connecticut, and Idaho did not have nationally significant sites on the registry located in high-risk flood regions; as such they are absent from the national list.

Keep reading to see which historic sites are at risk of flooding in your state, or explore the national list with an interactive map here. Â鶹ԭ´´ is also publishing the raw data it merged to produce this story, available on and .

Michigan by the numbers

- Historically significant buildings with risk of river flooding: 4
--- Commandant's Quarters, Dearborn (relatively high risk)
--- All Saints' Episcopal Church, Saugatuck (relatively high risk)
--- Herbert H. Dow House, Midland (relatively high risk)

Built in 1899, the and gardens belonged to Herbert Dow, the founder of Dow Chemical Company, and his wife, Grace. In 2020, the town of Midland experienced a —an event only likely to occur every 500 years—that destroyed a power dam and forced over 10,000 people to evacuate their homes. The flooding also raised concerns for when the floodwaters mixed with chemicals at the Dow Chemical plant, a location already designated a .

Now that you know how many sites are at risk in your state, continue reading to see which states have the most historic sites at risk of flooding.

States with the most historic sites at risk of flooding

1. Florida: 32 historically significant buildings with risk of flooding
2. New York: 28 historically significant buildings with risk of flooding
3. Arizona: 24 historically significant buildings with risk of flooding
4. Pennsylvania: 22 historically significant buildings with risk of flooding
5. Texas: 21 historically significant buildings with risk of flooding