What is the formal name for the 250th anniversary of a major event, such as America’s 2026 anniversary?

The formal name for a 250th anniversary, including America’s 2026 anniversary, is semiquincentennial.

The word combines Latin-derived elements associated with half of five hundred. In the United States, the term refers to the 250th anniversary of the Declaration of Independence, adopted on July 4, 1776. The anniversary is commonly branded as America250 or America 250.

The terminology can be confusing because anniversary names are not always used consistently. A centennial marks 100 years, a sesquicentennial marks 150 years, and a bicentennial marks 200 years. A semiquincentennial specifically marks 250 years.

America’s semiquincentennial is scheduled for 2026, exactly 250 years after the Declaration’s adoption. The term describes the anniversary itself, not a separate founding document, political institution, or celebration venue. That distinction makes it the precise answer when a question asks for the name of the 250-year milestone.