In Alamogordo, New Mexico, on July 16, 1945

The "Trinity" test was the first test of a nuclear weapon, conducted by the United States on July 16, 1945 at 33.675° N 106.475° W, thirty miles (48 km) southeast of Socorro on what is now White Sands Missile Range, headquartered near Alamogordo, New Mexico. It was a test of an implosion-design plutonium bomb, the same type of weapon later dropped on Nagasaki, Japan. The detonation was equivalent to the explosion of around 20 kilotons of TNT, and is usually credited as the beginning of the Atomic Age.