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

The 1976 U.S. anniversary observance was called the United States Bicentennial.

The Bicentennial marked 200 years since the Declaration of Independence in 1776. Unlike the 1876 Centennial Exposition, which concentrated much attention in Philadelphia, the 1976 observance involved nationwide events, public art, educational programs, parades, and specially designed memorabilia.

The period produced a distinctive visual culture of red, white, and blue graphics, along with commemorative coins and postage stamps. The American Revolution Bicentennial Administration coordinated federal participation, while states, cities, museums, schools, and private organizations developed local programs.

“Bicentennial” means a 200th anniversary. The comparable terms for the earlier milestones are “centennial” for 100 years and “sesquicentennial” for 150 years. America250, marking 250 years, is therefore the next major national anniversary after the Bicentennial rather than a repetition of it.