Constitution Day (or Citizenship Day) recognizes the ratification of the United States Constitution and those who have become U.S. citizens. It is observed on September 17, the day the U.S. Constitutional Convention signed the Constitution in 1787.
You can learn more at the National Endowment for the Humanities’ Constitution Day site.
The Allegheny College Center for Political Participation hosts an annual event to encourage the Allegheny Community to learn more about the Constitution and it’s impact on American life.
Text of the Constitution
(from the National Archives Web site)