The U.S. Constitution took effect on March 4, 1789. This foundational document outlines the structure of the U.S. government, including the separation of powers among the legislative, executive, and judicial branches. The Constitution established the rule of law and defined the rights of citizens, thus becoming a lasting symbol of American democracy. The Bill of Rights, ratified in 1791, further expanded protections for individual freedoms. The Constitution serves as a critical legal framework that has guided the governance of the United States for over two centuries.