What standard term for a 250th anniversary is used for America250?

The standard term for a 250th anniversary used for America250 is semiquincentennial.

The word combines “semi,” meaning half, with “quincentennial,” relating to 500 years. Together, the term describes half of a millennium, or 250 years. The United States Semiquincentennial is the formal name for the national anniversary observed on July 4, 2026.

Other terms have appeared in historical and public usage, including sestercentennial, bisesquicentennial and quarter millennium. However, semiquincentennial is the name used in the title of the federal commission and in much official planning for America250.

The terminology can be confused with bicentennial, which means 200 years, or sesquicentennial, which means 150 years. Tricentennial refers to 300 years, making it a future milestone for the United States.