We celebrate Constitution Day to honor the signing of the United States Constitution, which took place on September 17, 1787. This day is significant because the Constitution established the framework of the U.S. government, defining the separation of powers among the three branches of government and securing fundamental individual liberties that protect democratic freedoms. Constitution Day also celebrates U.S. citizenship and serves as a reminder to citizens of their rights and duties under the Constitution. It is observed annually on September 17 to commemorate the historic signing that formed the foundation of the United States as a unified nation with a functioning government.