The formal anniversary term for America's 250th anniversary is semiquincentennial.
The word combines Latin-derived elements associated with half of 500, producing the meaning “250th anniversary.” It is used for the 2026 commemoration of the Declaration of Independence and is the formal name behind the America250 initiative.
The term is less familiar than bicentennial, which means a 200th anniversary, and sesquicentennial, which means a 150th anniversary. Other labels have appeared in public discussion, including sestercentennial and quarter millennium, but semiquincentennial is the standard name used for the national observance.
The United States Semiquincentennial Commission was created to help organize and coordinate the observance. The commission’s work covers the Revolution as well as the broader history of the United States leading to the 250th anniversary.