I can't seem to find that in my copy of the U. S. Constitution. As a matter of fact, this Country's founders even made reference to the population overthrowing an oppressive government. Under the Articles of Confederation AND the U. S. Constitution is WAS understood that the individual states had made a VOLUNTARY pact from which they could withdraw if it was in their best interest. Go back and read the Federalist and Anti-Federalist Papers for further explanations regarding the LIMITED powers of the FEDERAL government and then realize that the powers NOT enumerated were left to the individual STATES.
Look in the 10th amendment. The people retain the right to maintain the Union in perpetuity. So far, they have done so.
Walt