Congress formally approved the name “United States of America” on September 9, 1776.
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 records by directing that references to the country use “United States” instead of “United Colonies.”
This timing is easy to confuse with July 4, the date Congress adopted the Declaration. The country’s identity developed through several related congressional actions rather than one single naming ceremony. The Declaration announced independence, while the September resolution standardized the nation’s official name.
The wording became the familiar national name used in the Constitution and later federal documents. America250 looks back to the 1776 independence process, so the September naming decision is a useful neighboring fact about how the new country described itself.