For America250, what term means a 250th anniversary, including the United States’ 2026 milestone?

For America250, the term meaning a 250th anniversary is semiquincentennial.

The word combines semi-, meaning half, with quincentennial, meaning a 500th anniversary. Half of 500 is 250, so a semiquincentennial marks two and a half centuries. America250 uses the term for the national commemoration centered on July 4, 2026.

This milestone is distinct from a centennial, which marks 100 years, and a bicentennial, which marks 200 years. A sesquicentennial marks 150 years, while a tercentennial marks 300. The less common word quarter-millennium can also describe 250 years, but it is not the formal name used for the United States’ anniversary.

The United States Semiquincentennial Commission was established by Congress in 2016 to help coordinate the commemoration. Its work connects the 2026 anniversary with the Declaration of Independence adopted in 1776 and with events, exhibits, educational programs, and celebrations across the country.