Byelorussian Soviet Socialist Republic

The Byelorussian Soviet Socialist Republic (BSSR), Byelorussian SSR or Byelorussia; (Belarusian: Беларуская Савецкая Сацыялістычная Рэспубліка; Russian: Белорусская Советская Социалистическая Республика), also known as Soviet Belarus or simply Belarus, was a communist state from 1920 to 1922 and then a republic of the Soviet Union (USSR). It was one of fifteen constituent republics of the USSR from 1922 to 1991, with its own legislation from 1990 to 1991. The republic was ruled by the Communist Party of Byelorussia. It was also known as the White Russian Soviet Socialist Republic. Minsk was the capital and largest city of the republic.

Following the Treaty of Brest-Litovsk in March 1918, which ended Russia's involvement in World War I, the Belarusian Democratic Republic (BDR) was proclaimed under German occupation; however, as German troops left, the Socialist Soviet Republic of Byelorussia was established in its place by the Bolsheviks in December, and it was later merged with the Lithuanian Soviet Socialist Republic in 1919 to form the Socialist Soviet Republic of Lithuania and Belorussia, which ceased to exist as a result of the Polish occupation during the Polish–Soviet War. Following a peace treaty with Lithuania, the Socialist Soviet Republic of Byelorussia was re-founded on 31 July 1920 and later became known as the Byelorussian Soviet Socialist Republic.

The BSSR became one of the four founding members of the Soviet Union in December 1922, together with the republics of Russia, Transcaucasia, and Ukraine. Byelorussia was one of several Soviet republics occupied by Nazi Germany during World War II. It was one of the most developed and prosperous Soviet republics, due to its advanced manufacturing industry and agriculture. The BSSR overall was a net exporter, being a notable producer of consumer electronics, processed agricultural goods, potash, fertilizer, machinery, grain and military equipment. It was also one of the more advanced republics in terms of education and technological expertise. Towards the final years of the Soviet Union's existence, the Supreme Soviet of the Byelorussian SSR adopted the Declaration of State Sovereignty in 1990. In the referendum held on 17th March 1991, nearly 84% of the population voted in favor of preserving the USSR. Despite this, on 25 August 1991, the Byelorussian SSR declared independence, and on 19 September it was renamed the Republic of Belarus. The Soviet Union would eventually be formally dissolved on 26 December 1991.

Geographically, the Byelorussian SSR after 1945 was bordered by Russian SFSR to the east and northeast, Ukraine to the south, Poland to the west, and Lithuania and Latvia to the northwest. The republic spanned an area of 207,600 square kilometres (80,200 sq mi) with a population of 10 million as of 1989. Belarusians formed the majority of the population, followed by significant minorities of Russians, Poles, Ukrainians and Jews. The official languages of the BSSR were Belarusian and Russian.