The Union of Soviet Socialist Republics[a] (USSR),[b] commonly known as the Soviet Union,[c] was a socialist federation in Eurasia that existed from 1922 to 1991. Nominally a union of multiple national Soviet republics,[d] its government and economy were highly centralized. The country was a one-party state, governed by the Communist Party with Moscow as its capital in its largest republic, the Russian Soviet Federative Socialist Republic (Russian SFSR). Russians dominated the USSR. Other major urban centres were Leningrad, Kiev, Minsk, Alma-Ata and Novosibirsk.