The Continental Congress adopted the Lee Resolution on July 2, 1776, formally resolving that the colonies should be independent.
Richard Henry Lee of Virginia introduced the independence resolution in June. Congress debated the proposal and postponed the final decision while delegates sought instructions from their colonial governments. On July 2, the resolution passed and declared that the United Colonies were free and independent states.
The Declaration of Independence followed two days later, on July 4. That timing explains why John Adams believed July 2 would become the celebrated independence holiday, even though July 4 ultimately became the date associated with the declaration and America250.
The resolution and the declaration had different roles. The Lee Resolution made the formal political decision, while the Declaration explained the reasons for that decision and presented them to the public and the world.