What is the formal term for America’s 250th anniversary, celebrated by America250?

The formal term for America’s 250th anniversary, celebrated by America250, is semiquincentennial.

The word combines “semi,” meaning half, with “quincentennial,” meaning a 500th anniversary. Together, the term describes half of five centuries, or 250 years. It is a less familiar anniversary word than bicentennial, which means 200 years.

The United States Semiquincentennial commemorates the 250th anniversary of the Declaration of Independence. The principal anniversary date is July 4, 2026, exactly 250 years after the Second Continental Congress approved the Declaration in Philadelphia.

Several alternative terms appear in historical and reference writing, including sestercentennial, bisesquicentennial, and quarter millennium. However, “United States Semiquincentennial” is the official title used for the national observance and is the term associated with the America250 commission.