Popular Sovereignty is government based on the people basically. The people of the United States give the government the power they have. Government in a democracy, can only remain having power if they do not disregard the will of the people. Popular sovereignty has been around since the creation of the United States, and was founding principle for the country.
There are different ways that popular sovereignty is expressed in a democracy. First, the people are involved in the making of a constitution. Second, the constitution made in the name of the people is ratified by a majority vote of the people or representatives elected by the people. Third, the people indicate support for their government when they vote in elections, uphold the constitution and basic principles of government, and work to influence public policy positions. Lastly, people are involved directly or indirectly with proposing and ratifying amendments.