What is the formal name for America250's 250th-anniversary event?

The formal name for America250's 250th-anniversary event is the United States Semiquincentennial.

The word combines “semi,” meaning half, with “quincentennial,” meaning a 500th anniversary. Together, the term describes 250 years, or half of five centuries. The event is also called the Bisesquicentennial, Sestercentennial, or Quarter Millennium, though Semiquincentennial is the most widely used formal term.

America250 is the public-facing brand associated with the United States Semiquincentennial Commission. The celebration honors the 250th anniversary of the Declaration of Independence rather than the anniversary of the Constitution, which was written in 1787.

This distinction matters because the United States has several major founding milestones. The 1976 bicentennial marked 200 years since 1776, while 2026 marks 250 years since the Declaration's adoption.