The Second Continental Congress passed the Lee Resolution on July 2, 1776, before America250's founding anniversary.
Introduced by Virginia delegate Richard Henry Lee, the resolution declared that the United Colonies were free and independent states and no longer politically connected to Great Britain. Congress adopted it after debate, with New York abstaining because its delegates lacked authorization at that moment.
The Declaration of Independence followed as a written explanation of the decision. Congress approved the declaration's final wording on July 4, which is why Independence Day is celebrated on that date rather than July 2.
John Adams thought July 2 would become the great annual holiday. His prediction was understandable because the Lee Resolution made the formal break, but public celebration eventually centered on the Declaration's adoption date.