On what date did the USSR dissolve?

The dissolution of the Soviet Union occurred on December 26, 1991 officially granting independence to the 15 republics of the USSR.

On December 25, 1991 Mikhail Gorbachev resigned as leader of the USSR and declared his office extinct. Gorbachev handed over his powers including control of all nuclear weapons to Boris Yeltsin the President of Russia. From August to December of 1991 all the republics had either seceded or denounced the treaty that had created the USSR.

The 15 republics that comprised the USSR were, Armenia, Azerbaijan, Belarus, Estonia, Georgia, Kazakhstan, Kyrgyzstan, Latvia, Lithuania, Moldova, Russia, Tajikistan, Turkmenistan, Ukraine, Uzbekistan.