Three Mile IslandCNN
On March 29, 1979, the worst nuclear accident in U.S. history took place in Pennsylvania when large amounts of reactor coolant and radioactive gasses from the Three Mile Island nuclear power plant were released into the environment. Within days of the accident, 140,000 people evacuated their homes within a 20-mile radius of the plant. The accident brought widespread attention to reactor safety and large protests from anti-nuclear groups. Cleanup from the accident began in August 1979 and was not completed until December 1993.