The foundation of our American Government, its purpose and form and structure are found in the Constitution of the United States. The Constitution, written in 1787, is the "supreme law of the land" because no law may be passed that contradicts its principles. No person or government is exempt from following it.
The Constitution establishes a federal democratic republic form of government. That is, we have an indivisible union of 50 sovereign States. It is a democracy because people govern themselves. It is representative because people choose elected officials by free and secret ballot. It is a republic because the Government derives its power from the people.
The purpose of our Federal Government, as found in the Preamble of the Constitution, is to "establish Justice, insure domestic Tranquility, provide for the common defense, promote the general Welfare, and secure the Blessings of Liberty to ourselves and our posterity." In order to achieve this purpose the Founding Fathers established three main principles on which our Government is based: