Constitution Day commemorates the adoption of the United States Constitution and celebrates the citizens of the United States.
Constitution or Citizenship Day is observed annually on September 17th, the same day as the US Constitution was signed in 1787.
At first on 1939 President Harry Truman declared that the third Sunday of May become the "I am American Day".
fter 10 years, 1953, President Dwight Eisenhower changed the date to match with the marking of the Constitution and renamed it Citizenship Day.
17th September was chosen as the Constitution Day because on this day in the year 1787 the US Constitution was duely signed.