Conflict between the colonies and England was already a year old when the colonies convened a Continental Congress in Philadelphia in the summer of 1776. In a June 7 session in the Pennsylvania State House (later Independence Hall), Richard Henry Lee of Virginia presented a resolution with the famous words: “Resolved: That these United Colonies are, and of right ought to be, free and independent States, that they are absolved from all allegiance to the British Crown, and that all political connection between them and the State of Great Britain is, and ought to be, totally dissolved.”
On July 2nd, 1776, the Continental Congress voted in favor of independence, and two days later delegates from the 13 colonies adopted the Declaration of Independence, a historic document drafted by Thomas Jefferson. An event that which eventually led to the formation of the United States of America.
History of Independence Day, the 4th of July (Military.com)