What does “semiquincentennial” mean in the United States Semiquincentennial’s name?

“Semiquincentennial” means a 250th anniversary.

The word combines semi-, meaning half, with quincentennial, meaning a 500th anniversary. Half of 500 years is 250 years, so the term describes the United States’ 250-year anniversary in 2026.

Several other labels have been used for the same milestone. These include sestercentennial, bisesquicentennial, and quarter millennium. Semiquincentennial is the name most prominently associated with the federal America250 commemoration.

The terminology can be confusing because anniversary words are not always used consistently. Bicentennial means 200 years, sesquicentennial means 150 years, and centennial means 100 years. The United States’ 2026 observance is distinct from the 1976 bicentennial, which commemorated 200 years since the Declaration of Independence.