Research assistant Council Foreign Relations, 1936-1937, Institute Pacific Relations, 1938-1939. Research associate Johns Hopkins, 1939-1941, associate geography, 1942-1944. Senior regional specialist Office of War Information, 1944-1945.
Agricultural economist Office Foreign Agricultural Relations, Department Agriculture, 1945-1947. Associate professor of geography Yale, 1947-1952, professor, 1952-1977, department chairman geography, director Southeast Asia Studies Program, 1958-1977. Fulbright research professor, Philippines, 1950.
Ford fellow, Indonesia, 1955-1956. Fulbright-Hays fellow, Malaysia, 1968.