What is the formal name for the 250th anniversary commemorated by America250?

The formal name for the 250th anniversary commemorated by America250 is the United States Semiquincentennial.

“Semiquincentennial” combines roots referring to half of five hundred, producing a 250-year anniversary. The term is less familiar than “bicentennial,” but it is the name used for the nationwide commemoration of the 250th anniversary of American independence.

The event also has alternative names, including sestercentennial, bisesquicentennial, and quarter millennium. These terms can appear in historical writing, but America250 and United States Semiquincentennial are the principal labels associated with the 2026 observances.

The word does not mean the anniversary of the Constitution alone or the founding of a particular state. It refers specifically to the 250th anniversary of the Declaration of Independence and the United States’ independence celebration.