In 1952, President Harry S. Truman signed a bill that moved I Am an American Day from the third Sunday in May to September 17. Truman did so in order for the holiday to coincide with the date of the signing of the U.S. Constitution in 1787. Congress renamed the holiday Citizenship Day.

A joint resolution passed in 1956 requested that the president proclaim the week beginning September 17 and ending September 23 each year as Constitution Week. In 2004, Senator Robert C. Byrd of West Virginia entered an amendment to the Consolidated Appropriations Act of 2005 to change the name of the September 17 holiday to Constitution Day and Citizenship Day. The purpose of Constitution Day and Citizenship Day is to commemorate the creation and signing of the supreme law of the land and to honor and celebrate the privileges and responsibilities of U.S. citizenship for both native-born and naturalized citizens.

Learn more about Constitution Day from the Center for Civic Education! http://www.civiced.org/home