At the height of the Cold War, the NTS was the primary location for the United States’ above-ground nuclear weapons tests. After the 1963 Limited Test Ban Treaty severely curtailed these activities. most nuclear tests were conducted underground.

More than 1,000 announced and unannounced nuclear detonations took place on the NTS. The explosive power of these tests ranged from the equivalent of a few tons of TNT to several megatons. One underground detonation was so powerful it created the Sedan Crater, perhaps the world’s largest man-made crater.

The site incorporates airfields and various nuclear research, development and testing facilities, including the Mercury Operation Support Facility, the U1a Complex, the Device Assembly Facility and the NTS Tour Center.

During the nuclear testing era, thousands of military personnel, scientists and support staff worked on the NTS. Many of them were directly exposed to toxic radiation and materials released by the tests.

Since then, thousands more have served on the NTS and elsewhere on the NTTR. They continue to be exposed to residual radiation and other contaminants in the air, soil and water supply that will remain highly dangerous for centuries.

Nuclear contamination extends beyond the borders of the NTS. Studies have indicated increased rates of certain cancers among military and civilian personnel stationed near the NTS, as well as residents living in communities outside the NTTR.