The historic document that served as a blueprint for governance in the United States is the Constitution of the United States. Drafted in 1787 and ratified in 1788, the Constitution established the framework for the federal government, delineating the powers and responsibilities of its three branches: the legislative, executive, and judicial. It embodies principles such as separation of powers, checks and balances, and individual rights, which have played a crucial role in American governance. The Constitution has underwent amendments, allowing it to evolve and address contemporary issues while remaining a foundational document that guides the nation's legal and political systems.