What is the standard name for the United States’ 250th anniversary?

The standard name for the United States’ 250th anniversary is the Semiquincentennial.

The word combines semi-, meaning half, with quincentennial, meaning a 500th anniversary. In this context, it describes half of a millennium, or 250 years. America250 is the shorter branding used by the official United States Semiquincentennial Commission and its national programs.

Several alternative terms also appear in historical and media coverage, including sestercentennial, bisesquicentennial, and quarter millennium. Semiquincentennial is the most widely used formal label for the 2026 observance.

The name is easy to mix up with bicentennial, which means 200 years, and sesquicentennial, which means 150 years. The United States celebrated its bicentennial in 1976 and its sesquicentennial in 1926. The 2026 observance therefore uses a different anniversary term and marks the nation’s 250th year since independence.