In 1922, the Harmon Foundation funded parks in 34 states. In 1926, the Foundation began recognizing African-American achievements in music, visual arts, literature, and more — sponsoring the first exhibition of works by African-American artists in 1928, touring the country by 1931. A key Harlem Renaissance program.

William died in 1928 in Southport, Connecticut. The New York Times revealed that the mysterious "Jedediah Tingle" was William Harmon.