The document that established the framework for the U.S. government is the Constitution of the United States, which was signed in 1787 at the Constitutional Convention in Philadelphia. This foundational document outlines the structure of the government, including the separation of powers among the legislative, executive, and judicial branches. It also enumerates the rights of citizens and provides guidelines for amendments. The Constitution was ratified in 1788 and has been amended several times since. It remains a cornerstone of American democracy and legal framework, influencing many other democratic governments around the world.