The significant document ratified in 1788 that outlined the structure of the U.S. government is the United States Constitution. After the Constitutional Convention of 1787, the Constitution aimed to create a stronger federal government to address the weaknesses of the Articles of Confederation. It established the framework for the separation of powers among three branches: legislative, executive, and judicial, while also including checks and balances to prevent any one branch from becoming too powerful. The Constitution became the supreme law of the land, embodying principles such as federalism and individual rights, and has served as a guiding document for American governance ever since.