March 1976 During a series of high-yield tests conducted during this month, two ranges were added, and the 200 to 1,000 kt range was dropped. 200 to 500 kt 500 to 1,000 kt Since March 1976 On March 31, 1976, the Soviet Union and the United States agreed to limit the maximum yield of underground tests to 150 kt. The yield ranges now reported are: Less than 20 kt Less than 150 kt 20 to 150 kt Locations The first test of a nuclear weapon was in the atmosphere on July 16, 1945, in a remote part of New Mexico on what was then the Alamogordo Bombing Range, and is now the White Sands Missile Range. The site is 55 miles northwest of Alamogordo, New Mexico. At various times between June 1946 and November 1962, atmospheric and underground tests were conducted by tha United States in the Marshall Islands, Christmas island, Johnston Atoll in the Pacific Ocean, and over the South Atlantic Ocean. Between January 1951 and July 1962, atmospheric and underground nuclear tests were conducted at the NTS. Since July 1962, all nuclear tests conducted in the United States have been underground and most of them have been at the NTS. Some tests were conducted on the Neliis Air Force Base Bombing Range; in central and northwestern Nevada; in Colorado, New Mexico, and Mississippi; and on Amchitka, one of the Aleutian Islands off the coast of Alaska. T ind Pur; The definition of terms used in this document appears in the Giossary. Type refers to the method of deployment of the nuciear device at time of detonation such as tower, tunnel, airdrop, etc. Purpose indicates whether the test was part of the weapons development program, a DoD effects test, a joint United States-United Kingdom (US-UK)test, or was part of some special program that involved the use of nuclear devices. In the Summary, the sum of all tests conducted underground (tunnel, shaft, and crater events) appears as Total Underground. With the exception of five underwater tests, the remaining events appear as Total Atmospheric.