The historic document that declared the 13 American colonies independent from Britain is the Declaration of Independence. Adopted on July 4, 1776, it was primarily authored by Thomas Jefferson and reflects Enlightenment ideals about individual rights and government by consent. The Declaration outlined grievances against King George III and emphasized the colonies' desire for freedom and self-governance. Its adoption sparked the American Revolutionary War, leading to the eventual establishment of the United States. Today, July 4th is celebrated as Independence Day, a national holiday in the U.S.