Popular sovereignty

Popular sovereignty is the idea that the power of a state and its government are created and sustained by the permission of its people. They give their permission through their elected representatives (Rule by the People), who is the source of all political power. It is very similar to a social contract, with philosophers such as Thomas Hobbes, John Locke and Jean-Jacques Rousseau.
Americans created their Revolution and government on popular sovereignty. In the 1850s Popular sovereignty in the United States meant a very controversial way to deal with slavery in the territories. This was pushed by senator Stephen A. Douglas. It meant that people living in a territory would be the ones to decide if slavery would be allowed. It led to fighting in Bleeding Kansas. This was because abolitionists (people who didn't want slavery) and pro-slavery people came to the Kansas territory in order to decide the elections. 
Popular sovereignty also can be described as the "voice of the people."