Before coming to Texas State, Sansom was executive director of the Texas Parks and Wildlife Department, where in 1997 he was one of the state leaders instrumental in the passage of Senate Bill 1, landmark legislation affecting the development and management of water resources in Texas. He also created the Parks and Wildlife Foundation of Texas, which funds a number of department programs through private donations, and new urban fish and wildlife programs designed to promote conservation awareness in urban areas.
Early in his career, Sansom worked for the National Recreation and Park Association in Washington, D.C. He has served as environmental coordinator for the White House Conference on Youth; special assistant to Interior Secretary Rogers C.B. Morton; director of conservation education at the Federal Energy Administration; and deputy director of the Energy Institute at the University of Houston.
Sansom has also served as executive director of the Texas Nature Conservancy, and on the board of trustees of the Texas Historical Foundation, Bat Conservation International, KLRU Public Television in Austin, and the National Audubon Society. He has written for numerous publications and is the author of six books.