http://en.wikipedia.org/wiki/Constitution_Day_(United_States)
Constitution Day (or Citizenship Day) is an American federal observance that recognizes the ratification of the United States Constitution, and also recognizes all who have become citizens due to either coming of age or naturalization. It is observed on September 17, the day the U.S. Constitutional Convention signed the Constitution in 1787.
“We the People of the United States, in Order to form a more perfect Union, establish Justice, insure domestic Tranquility, provide for the common defence, promote the general Welfare, and secure the Blessings of Liberty to ourselves and our Posterity, do ordain and establish this Constitution for the United States of America... Done... the seventeenth day of September, in the year of our LORD one thousand seven hundred and eighty seven.” —George Washington and the delegates
Today, 17 September, marks the 221st anniversary of the Constitution’s signing by our nation’s Founders.