On the State Level
In the United States, 23 states have provisions for referendum and initiative on the statewide level. In 49 states, amendments to the state constitutions must be approved in a referendum.
On the National Level
National Referendums have taken place in many countries, including Canada, England, Ireland, Italy, France, Denmark, and South Africa. Many countries have solved "unsolvable" problems by holding National Referendums. In South Africa, a national referendum led to the end of apartheid. In Ireland, national referendums have brought peace and stability.
James Madison, a signer of the United States Constitution and the 4th President of the United States, believed that the "supreme authority" is the people.