USSR stands for the Union of Soviet Socialist Republics, which was also known as the Soviet Union. The USSR existed from 1922 until 1991. Following a long revolution and civil war that overthrew the Russian monarchy, it was established as a confederation of Russia, Belorussia, Ukraine and the Transcaucasian Federation.
The Soviet Union made up a total land area of 8,649,500 square miles, making it comparable to the size of North America and the world's largest state during its existence. It had a border spanning 37,000 miles, and its highest peak, Communism Peak (now known as Ismoil Somoni Peak), measured 24,590 feet.