What is the formal anniversary term for the United States’ 250th anniversary in America250?

The formal anniversary term for the United States’ 250th anniversary in America250 is semiquincentennial.

The word combines roots meaning half and five hundred, producing the sense of half of 500, or 250. It is used for the anniversary of the Declaration of Independence and the national celebrations planned for 2026.

Several less common alternatives exist. Sestercentennial and quarter millennium can also describe 250 years, while bisesquicentennial is another historical term. These competing labels can make the vocabulary of the anniversary seem more complicated than the underlying fact.

America250 is the branding used by the United States Semiquincentennial Commission and related national programs. The previous major milestone was the bicentennial in 1976, a term that means 200th anniversary. The next 100-year milestone after 2026 will be the tricentennial in 2076.