Constitution Day and Citizenship Day is observed each year on
September 17 to commemorate the signing of the Constitution on September
17, 1787, and “recognize all who, by coming of age or by
naturalization, have become citizens.”
This commemoration had its origin in 1940, when Congress
passed a joint resolution authorizing and requesting the President to
issue annually a proclamation setting aside the third Sunday in May for
the public recognition of all who had attained the status of American
citizenship. The designation for this day was “I Am An American Day.”