1977 – The Kelly Barnes Dam, located above Toccoa Falls Bible College near Toccoa, Georgia, fails, killing 39.
1971 – The United States Atomic Energy Commission tests the largest U.S. underground hydrogen bomb, code-named Cannikin, on Amchitka Island in the Aleutians.
1944 – Plutonium is first produced at the Hanford Atomic Facility and subsequently used in the Fat Man atomic bomb dropped on Nagasaki, Japan.