Actually, the U.S. never was. We have never been a Democracy. A democracy can be thought of as 4 wolves and a sheep voting on what to have for dinner. The U.S.A. is a democratic Republic. The ‘democratic’ part means that we elect our leaders in a majority vote. The republic part means we are under the rule of law and our elected representatives are accountable to us.
Here is a video that explains the different forms of government. It does a pretty good job of explaining the difference between a democracy and a republic.
I just wish that this video were played in every Social Studies class in the country at least once a year.