The United States Declaration of Independence was adopted in 1776, the founding year commemorated by America250.
The Second Continental Congress approved the Declaration on July 4, 1776. The document announced that the thirteen American colonies regarded themselves as free and independent states rather than colonies of Great Britain.
The Declaration followed the Lee Resolution, which Congress approved on July 2, 1776. That earlier resolution formally declared independence, while the Declaration explained the reasons for the break and presented political principles supporting it.
A common mix-up concerns adoption and signing. Congress adopted the final text on July 4, but most delegates signed the famous engrossed parchment copy primarily on August 2, 1776. The America250 anniversary is generally dated from the 1776 adoption of the Declaration.