What document’s signing did the United States Semiquincentennial commemorate?

The United States Semiquincentennial commemorated the signing of the Declaration of Independence.

The Declaration announced that the thirteen American colonies regarded themselves as independent states and explained their political reasons for separating from Great Britain. It was adopted by the Second Continental Congress in Philadelphia on July 4, 1776, and is the founding document most directly associated with Independence Day.

The anniversary wording can cause confusion because independence-related events happened on several different dates. Congress voted for independence on July 2, the Declaration was formally adopted on July 4, and the surviving engrossed document was signed by delegates beginning on August 2. America250 conventionally centers the anniversary on July 4, 1776.

The commemoration did not mark the signing of the Constitution, which occurred in 1787, or the Treaty of Paris, which ended the Revolutionary War in 1783. Those documents are important to U.S. history but represent different milestones.