Armenia declared its independence from the Soviet Union on August 23, 1990, having previously been the Armenian Soviet Socialist Republic, one of the constituent republics of the USSR since 1936, and part of the Transcaucasian Soviet Federated Socialist Republic since 1920. In the wake of the August Coup (1991), a referendum was held on the question of secession. Following an overwhelming vote in favor, full independence was declared on September 21, 1991. However, widespread recognition did not occur until the formal dissolution of the Soviet Union on December 25, 1991. The United States recognized Armenia on December 25, 1991.