Fall of the Soviet Union

By 1990, many republics in the Union of Soviet Socialist Republics began declaring independence from Moscow.

The first to declare independence was Poland. After a successful decade of resisting Soviet influence, Poland elected its first president, Lech Wałęsa in 1990.

The Baltic republics came next. And then Ukraine.
Boris Yeltsin
Kremlin.ru [CC BY 3.0 via Wikimedia Commons

In 1991, Russia elected Boris Yeltsin as its first democratically elected leader . He was instrumental in thwarting an attempted coup of Soviet supreme leader, Mikhail Gorbachev.

But Gorbachev's time was over.  Ironically, his reforms of the 1980s helped bring about an end to the Soviet Union.  The official announcement of the dissolution of the Soviet Union came on December 17, 1991 and after Gorbachev's official resignation, the USSR was no more.

The Cold War was over.

Why did the Soviet Union collapse?

The main reason for the collapse of the Soviet Union had extreme economic problems due to Cold War.  Their  economy was not able to keep up with the spending necessary to engage in the arms race and the wars. Although the United States was spending much money too, the economy of the United States better supported the spending.

In the end, the Soviet Union couldn't afford itself any longer.