The famous document that proclaimed the independence of the American colonies is the Declaration of Independence, adopted on July 4, 1776. Drafted primarily by Thomas Jefferson, the document articulates the colonies' grievances against King George III and asserts the right to self-governance. It eloquently states the principles of individual liberty and the idea that governments derive their just powers from the consent of the governed. The Declaration not only marked the official break from British rule but also inspired movements for independence worldwide, solidifying its importance in history.