Gerald Ford was the U.S. president during the 1976 Bicentennial, the previous major anniversary before America250.
Ford became president in August 1974 after Richard Nixon resigned. He was therefore in the White House when the United States celebrated 200 years of independence in 1976. Ford presided over national Bicentennial ceremonies and addressed the country during the anniversary year.
The Bicentennial occurred during a period of political and economic uncertainty, only a few years after the Watergate scandal and the end of U.S. involvement in the Vietnam War. The nationwide celebrations nevertheless emphasized historical continuity and national identity.
Jimmy Carter won the 1976 presidential election and took office in January 1977. That timing makes him a frequent wrong answer: he was elected during the Bicentennial year but was not president for its July 4 climax.