What is the official anniversary term for the United States reaching 250 years in 2026?

The official anniversary term for the United States reaching 250 years in 2026 is semiquincentennial.

The word describes half of a quincentennial: “semi” means half, while “quincentennial” refers to a 500th anniversary. Together, the parts indicate 250 years. The term is less familiar than bicentennial, which describes 200 years, but it is the formal label used for the national 250th-anniversary observance.

Several alternative terms exist. Sestercentennial is another established word for a 250th anniversary, while quarter-millennium describes one quarter of 1,000 years. Bisesquicentennial is also used occasionally. These alternatives can cause confusion, but they describe the same length of time.

The United States Semiquincentennial is tied to the 250th anniversary of American independence and the Declaration of Independence. The America250 organization and related federal planning efforts use the anniversary to connect history, civic education, public events, and commemorative projects across the country.