James K. "Tex" Lewis was born on October 24, 1924, in Waco, Texas. He obtained a Bachelor of Science in Animal Science from Colorado State University in 1948 and a Master of Science in Animal Science from Montana State College in 1951. Lewis pursued graduate studies in range management at Texas A&M University.

Lewis assumed the role of professor of Animal Sciences at South Dakota State University, focusing on teaching and research in range management and range livestock nutrition. Lewis conducted grazing, supplementation, and range improvement studies at the Cottonwood Range Field Station and Antelope Range Field Station, including biometric analyses of grassland ecosystems. Recognitions include the Special Appreciation Award from the South Dakota Section of the Society for Range Management in 1975, the Trail Boss Award in 1980, and the Outstanding Achievement Award from the Society of Range Management in 1984.

James K. "Tex" Lewis retired from South Dakota State University in 1985, leaving behind a legacy in range management.