The U.S. Constitution went into effect on March 4, 1789. Following its ratification by the necessary nine states, the Constitution established the framework for the federal government of the United States, replacing the Articles of Confederation. It set forth the principles of democracy and rule of law, establishing a system of checks and balances among the three branches of government: the executive, legislative, and judicial. The Constitution has since been amended several times to adapt to changing societal values and needs, but its core structure and principles continue to guide American governance today.