American Democracy is called the Great Experiment because the Framers designed something that never happened until that moment. There was no democracy like the one they created so they did not know if it was going to work or not. Most of the countries until that moment were adopted the Parliamentary system and did not divide the country into states. The US went to a completely different way and adopted the Federalist system, which also gave powers to the States at the same time that it adopted the bicameral legislative with the creation of the Executive Power with the President.