Constitution Day and Citizenship Day is an American federal observance that recognizes the adoption of the United States Constitution and those who have become U.S. citizens. It is normally observed on September 17, the day in 1787 that delegates to the Constitutional Convention signed the document in Philadelphia. The United States Congress designated September 17 as Constitution Day and Citizenship Day on February 29, 1952, by joint resolution (36 U.S.C. 106). It begins Constitution Week in the United States, which continues through September 23.
The law establishing the present holiday was modified in 2004 with the passage of an amendment by Senator Robert Byrd to the omnibus spending bill of 2004.