The Union of Soviet Socialist Republics (USSR) is formed.

The Union of Soviet Socialist Republics (USSR), commonly known as the Soviet Union, was a transcontinental country that spanned much of Eurasia from 1922 until it dissolved in 1991. During its existence, it was the largest country by area, extending across eleven time zones and sharing borders with twelve countries, and the third-most populous country. An overall successor to the Russian Empire, it was nominally organized as a federal union of national republics, the largest and most populous of which was the Russian SFSR. In practice, its government and economy were highly centralized. As a one-party state governed by the Communist Party of the Soviet Union (CPSU), it was the flagship communist state. Its capital and largest city was Moscow.

The Declaration and Treaty on the Formation of the Union of Soviet Socialist Republics officially created the Union of Soviet Socialist Republics (USSR), commonly known as the Soviet Union. It de jure legalised a political union of several Soviet republics that had existed since 1919 and created a new federal government whose key functions were centralised in Moscow. Its legislative branch consisted of the Congress of Soviets of the Soviet Union and the Central Executive Committee of the Soviet Union (TsIK), while the Council of People's Commissars composed the executive.