The United States Declaration of Independence is the pronouncement adopted by the Second Continental Congress meeting in Philadelphia, Pennsylvania, on July 4, 1776. The Declaration explained why the Thirteen Colonies at war with the Kingdom of Great Britain regarded themselves as thirteen independent sovereign states, no longer under British rule. With the Declaration, these new states took a collective first step toward forming the United States of America. The declaration was signed by representatives from New Hampshire, Massachusetts Bay, Rhode Island, Connecticut, New York, New Jersey, Pennsylvania, Maryland, Delaware, Virginia, North Carolina, South Carolina, and Georgia.

Support for independence was boosted by Thomas Paine's pamphlet Common Sense, which was published January 10, 1776 and argued for American self-government and was widely reprinted.^[29] To draft the Declaration of Independence, the Second Continental Congress appointed the Committee of Five, consisting of Thomas Jefferson, John Adams, Benjamin Franklin, Roger Sherman, and Robert Livingston.^[30] The declaration was written almost exclusively by Jefferson, who wrote it largely in isolation between June 11 and June 28, 1776, in a three-story residence at 700 Market Street in Philadelphia.^[31]

Identifying inhabitants of the Thirteen Colonies as "one people", the declaration simultaneously dissolved political links with Britain, while including a long list of alleged violations of "English rights" committed by George III. This is also one of the foremost times that the colonies were referred to as "United States", rather than the more common United Colonies.^[32]

On July 2, Congress voted for independence and published the declaration on July 4,^[33] which Washington read to his troops in New York City on July 9.^[34] At this point, the revolution ceased to be an internal dispute over trade and tax policies and had evolved into a civil war, since each state represented in Congress was engaged in a struggle with Britain, but also split between American Patriots and American Loyalists.^[35] Patriots generally supported independence from Britain and a new national union in Congress, while Loyalists remained faithful to British rule. Estimates of numbers vary, one suggestion being the population as a whole was split evenly between committed Patriots, committed Loyalists, and those who were indifferent.^[36] Others calculate the split as 40% Patriot, 40% neutral, 20% Loyalist, but with considerable regional variations.^[37]