Top Ten Worst U.S. Disasters of All Time

10. Three Mile Island Meltdown

9. 1974 Super Outbreak

8. 2010 Gulf Oil Spill

7. 1969 Anchorage, Alaska Earthquake

6. 2011 Super Outbreak

5. Columbia Space Shuttle Disaster

4. Mount St. Helens Eruption 1980

3. Challenger Explosion

2. 1906 San Francisco Earthquake

1. 9/11 Attacks