On July 4th, 1976, the Rockefeller Foundation announced "the Foundation’s bicentennial gift to the American people."
"Last March, 6,000 institutions dedicated to musical education and scholarship received a letter informing them that they had been chosen to receive as a gift from the Rockefeller Foundation a collection of one hundred specially produced records 'tracing the social and cultural history of the United States through its music.'”
You can read the article from the magazine RF Illustrated HERE (PDF).