The Declaration of Independence was the promise of a representative government; the Constitution was the fulfillment of that promise.
On July 4, 1776, the Second Continental Congress issued a unanimous declaration: the thirteen North American colonies would be the thirteen United States of America, free and independent of Great Britain. Drafted by Thomas Jefferson, the Declaration set forth the terms of a new form of government with the following words: "We hold these Truths to be self-evident, that all men are created equal, that they are endowed with certain unalienable Rights, that among these are Life, Liberty, and the Pursuit of Happiness."
Framed in 1787 and in effect since March 1789, the Constitution of the United States of America fulfilled the promise of the Declaration by establishing a republican form of government with separate executive, legislative, and judicial branches. The first ten amendments, known as the Bill of Rights, became part of the Constitution on December 15, 1791. Among the rights guaranteed by these amendments are freedom of speech, freedom of the press, freedom of religion, and the right to trial by jury. Written so that it could be adapted to endure for years to come, the Constitution has been amended only seventeen times since 1791 and has lasted longer than any other written form of government.