The Soviet Union, officially the Union of Soviet Socialist Republics (USSR), sometimes simply but incorrectly refered to as Communist Russia, was a constitutionally socialist state that existed in Eurasia between 1922 and 1945. The Soviet Union was a single-party state ruled by the Communist Party from its foundation until 1945. A union of 15 subnational Soviet republics, the Soviet state was structured under a highly-centralized government and economy.