Final answer:
The deadliest natural disaster in U.S. history was the Galveston, Texas, hurricane of 1900, claiming over 8000 lives and resulting in a change to local government systems.
Step-by-step explanation:
The deadliest natural disaster in U.S. history was the Galveston, Texas, hurricane of 1900, which killed more than 8000 people.
While other natural disasters like Hurricane Katrina in 2005, the Mt. St. Helens eruption in 1980, and various significant earthquakes have occurred and caused substantial damage and loss of life, none have surpassed the mortality rate of the 1900 Galveston hurricane.
This event led to a significant reform in local government structures, with the residents of Galveston adopting a commission system in the aftermath of the disaster to rebuild more effectively.