The historical document that established enduring legal principles and government structure in the United States is the Constitution. Ratified in 1788, it created a framework for a federal republic, outlining the separation of powers among the legislative, executive, and judicial branches. The Constitution embedded fundamental rights through the Bill of Rights, safeguarding civil liberties. This document not only provided a guideline for governance but also served as a model for democratic systems worldwide, promoting enduring concepts of checks and balances and rule of law.