The Ukraine's system of government was based on a one-party communist system ruled by the Communist Party of Ukraine, a part of the Communist Party of Soviet Union (KPSS). The republic was one of 15 constituent republics composing the Soviet Union from its entry into the union in 1922 until its dissolution in 1991. All of the political power and authority in the USSR was in the hands of Communist Party authorities, with little real power being concentrated in official government bodies and organs. In such a system, lower-level authorities directly reported to higher level authorities and so on, with the bulk of the power being held at the highest echelons of the Communist Party.