What is the official historical name for the United States’ 250th anniversary in 2026?

The official historical name for the United States’ 250th anniversary in 2026 is the United States Semiquincentennial.

A semiquincentennial marks 250 years. The term combines semi-, meaning half, with quincentennial, meaning a 500th anniversary. In practical terms, it describes half of a millennium, or a quarter of 1,000 years.

The anniversary commemorates the Declaration of Independence rather than the arrival of European settlers, the first colonial settlements, or the later ratification of the Constitution. Its central historical date is July 4, 1776, when Congress approved the Declaration.

Americans sometimes use less formal alternatives, including sestercentennial, bisesquicentennial, and quarter millennium. Bicentennial refers specifically to the 200th anniversary celebrated in 1976, while tricentennial will describe the 300th anniversary in 2076.