Thirteen colonies declared independence in the Declaration of Independence's original title.
The document was formally titled “The unanimous Declaration of the thirteen united States of America.” The thirteen were New Hampshire, Massachusetts, Rhode Island, Connecticut, New York, New Jersey, Pennsylvania, Delaware, Maryland, Virginia, North Carolina, South Carolina, and Georgia.
These colonies were British possessions along the Atlantic coast. Their representatives met in the Continental Congress, which first coordinated resistance and eventually declared separation from Great Britain. The phrase “united States” originally referred to these newly independent states rather than to a fully consolidated nation.
The number thirteen also survives in the United States flag's stripes. The red and white stripes represent the original colonies, while the stars represent the states in the Union. The number of stars has changed as new states joined, but the number of stripes remains thirteen.