Hoopes was a scholar of nineteenth- and twentieth-century American art, especially the work of Thomas Eakins, Winslow Homer, John Singer Sargent, and Marco Sassone.
Born in Philadelphia to Donelson Wood and Esther Taylor Dechert, Hoopes served in the United States Army from 1953 to 1955, rising to the rank of Sergeant.
Two years later, Hoopes curated the landmark exhibition there titled The Private World of John Singer Sargent.
[4] Hoopes also was nominated to serve on the Committee for the Preservation of the White House by United States President Jimmy Carter from 1977 to 1980.
Three years after that, Hoopes took the role of Director of the Thomas Cole National Historic Site, a post that he held until retirement in 1997.