By the turn of the 20th century, Emory College had produced several notable graduates. Alben W. Barkley, who graduated in 1900, represented Kentucky in the United States House of Representatives and in the Senate. In 1949, at age 71, he became the oldest Vice President of the United States in history. Thomas M. Rivers became one of the nation's premier virologists at the Johns Hopkins University Medical School, investigating encephalitis and smallpox and later leading the National Science Foundation's quest for a polio vaccine. Dumas Malone went on to become the head of Harvard University Press, one of the nation's leading academic publishers, and completed a Pulitzer Prize-winning six-volume study of Thomas Jefferson when he was over 90 years of age.