Nevada is site of first-ever underground nuclear explosion | September 19, 1957 | HISTORY

On September 19, 1957, the United States detonates a 1.7-kiloton nuclear weapon in an underground tunnel at the Nevada Test Site (NTS), a 1,375-square-mile research center located 65 miles north of Las Vegas. The test, known as Rainier, was the first fully contained underground detonation and produced no radioactive fallout. A modified W-25 warhead weighing 218 pounds and measuring 25.7 inches in diameter and 17.4 inches in length was used for the test. Rainier was part of a series of 29 nuclear weapons and nuclear weapons safety tests known as Operation Plumbbob that were conducted at the NTS between May 28, 1957, and October 7, 1957.