What was the name of the major U.S. anniversary celebration held in 1976, 50 years before America250?

The major U.S. anniversary celebration held in 1976 was the United States Bicentennial.

The Bicentennial commemorated the 200th anniversary of the Declaration of Independence. Its principal anniversary date was July 4, 1976, exactly 50 years before the 2026 semiquincentennial.

The observance was not limited to one ceremony. Official events began in April 1975 and culminated on July 4, 1976, with tens of thousands of celebrations and projects held across the United States and abroad. Parades, historical reenactments, fireworks, exhibitions, and the American Freedom Train were among its notable features.

The 1976 commemoration is the immediate historical predecessor to America250. The terms are easy to mix up: a bicentennial marks 200 years, while a semiquincentennial marks 250 years.