Congress formally approved the name “United States of America” on September 9, 1776, during the founding era commemorated by America250.
The phrase had already appeared in the Declaration of Independence, whose title referred to the thirteen united States of America. Congress later made the wording official in its own records by directing that “United Colonies” be changed to “United States” in documents and official materials.
This naming decision followed the July declaration process. The Lee Resolution established independence, the Declaration explained the decision, and the September action standardized the new nation’s name. These were related but separate congressional steps.
The name should not be confused with the later Constitution’s creation of the federal government. The Constitution was drafted in 1787 and took effect in 1789, more than a decade after the name was formally adopted.