Crawford Hallock Greenewalt (1902-1993) was a chemical engineer and the President of the DuPont Company from 1948 to 1962. Greenewalt was born in Cummington, Massachusetts, on August 16, 1902. He grew up in Philadelphia where he attended the William Penn Charter School before enrolling in the Massachusetts Institute of Technology where he received a B.S. degree. In 1926, Greenewalt married Margaretta Lammot du Pont (1902-1991), daughter of DuPont Company president Irenee du Pont. Greenewalt had begun his career at E.I. du Pont de Nemours in 1922 as a control chemist in the Philadelphia works. He was soon promoted to group leader, research supervisor, and assistant director of research. As assistant director of the Chemical Department (1939-1942), he set up the pilot plant for the production of nylon. In 1942 when the Du Pont Company agreed to participate in the Manhattan Project, Greenewalt was named chief liaison with the University of Chicago scientists. He also became technical director of the Hanford Engineering Works in Seattle, Washington. After the war, Greenewalt was named head of the Explosives Department, and in 1948 he became president, a position that he held for fourteen years.