On retirement from MIT in 1969, Smith became a professor emeritus of the History of Science and Technology, professor emeritus of Metallurgy and Humanities and Institute Professor Emeritus, an unusual title "reserved for only a few whose work transcends the boundaries of traditional departments and disciplines". He died of colonic cancer in his Cambridge, Massachusetts home on 25 August 1992. He was survived by his wife of sixty years, Alice Kimball Smith, his two children, Anne Smith Denman, chair of the Department of Anthropology at Central Washington University, and Stuart Marchant Smith, a marine geologist at the Scripps Institution of Oceanography, and a sister, Mary Smith. His papers are in the Niels Bohr Library in College Park, Maryland. His collection of antiquarian metallurgical texts was left to the Burndy Library at the Dibner Institute for the History of Science and Technology.