Congress formally approved the name “United States of America” on September 9, 1776.
The phrase had already appeared in the Declaration of Independence, whose formal title referred to the thirteen United States of America. Congress later adopted the name for official use, replacing the broader wartime description of the United Colonies.
This change occurred during the same summer as the declaration and the signing of its engrossed copy. It is easy to associate the national name exclusively with July 4, but the official naming action came more than two months later.
The wording reflected the political transformation underway. The colonies were no longer presenting themselves as territories within the British Empire; they claimed to be independent states acting together. The Articles of Confederation later provided a formal framework for that union, while the Constitution eventually replaced the Articles in 1789.