Glenn Thomas Trewartha (1896–1984) was an American geographer of Cornish American descent.
He graduated from the University of Wisconsin–Madison, with a Ph.D. in 1924. He taught at the University of Wisconsin.
He gave an address to the Association of American Geographers, "A Case for Population Geography." He also wrote about climate, explaining that the atmosphere was like "a pane of glass in a greenhouse... thus maintaining surface temperatures considerably higher than they otherwise would be."
- 1926 Guggenheim Fellowship
- "The earliest map of Galena, Illinois" Wisconsin Magazine Of History. Volume: 23 /Issue: 1 (1939–1940)
- A Reconnaissance geography of Japan, University of Wisconsin, 1934
- Elements of geography physical and cultural, Glenn Thomas Trewartha, Vernor Clifford Finch, Mc Graw-Hill, 1942
- Japan, a physical, cultural and regional geography, University of Wisconsin press, 1945
- An introduction to climate, McGraw-Hill, 1954
- Japan, a geography, Milwaukee: University of Wisconsin press, 1965
- An introduction to climate McGraw-Hill, 1968
- The More developed realm: a geography of its population, Editor Glenn Thomas Trewartha, Pergamon Press, 1978, ISBN 978-0-08-020631-8
- The Earth's problem climates, University of Wisconsin Press, 1981, ISBN 978-0-299-08230-7