What is the formal name for America's 250th anniversary?

The formal name for America's 250th anniversary is the United States Semiquincentennial.

The word combines “semi,” meaning half, with “quincentennial,” meaning a 500th anniversary. In practical usage, it identifies a 250-year anniversary of the United States Declaration of Independence. The official event is also promoted under the shorter public-facing name America250.

The term is less familiar than “centennial” or “bicentennial,” which describe 100- and 200-year anniversaries. Alternative labels recorded for the event include “bisesquicentennial,” “sestercentennial,” and “quarter millennium,” but “United States Semiquincentennial” is the principal title used for the national commemoration.

The anniversary is dated July 4, 2026, exactly 250 years after the Second Continental Congress adopted the Declaration of Independence. It is a commemoration of that 1776 event rather than a claim that every institution of the modern federal government began on the same day.