The 1990 Galveston Hurricane was the deadliest natural disaster to ever strike the US. It came on shore September 8, 1900 and killed somewhere between 6,000 and 12,000 people.
The storm surge was 15 feet high, which flooded the entire island. They have since built a seawall.
Adjusted to 2005 US Dollars, it was the second costliest Atlantic Hurricane.
Atmospheric CO2 was 296 ppm at the time.