The Sedan Crater is the site of a nuclear test (using a 104 kiloton thermonuclear device) that took place here on July 6, 1962. It was one of 27 tests undertaken by the Atomic Energy Commission, the predecessor to the U.S. Department of Energy, in its Plowshare Program. The program's purpose was to discern if and how nuclear explosions could be used for peaceful purposes, such as quarrying and large scale excavation. The explosive device was placed 635 feet underground and when it exploded, it displaced 12 million tons of earth and created a crater 1,280 feet in diameter and 320 feet deep. The strength of the explosion was 4.75 on the Richter Scale. Thirteen million people were affected by the radioactive fallout. The program finally ended in 1977. People are allowed to visit the site; there is an observation deck that sits on the edge of the crater. The crater was listed on National Register of Historic Places in 1994.