Don Barnett grew up in Rapid City and earned his undergraduate degree from South Dakota State University. While a graduate student at the University of Nebraska, he sought a direct commission and joined the US Army in 1967. As a commander in the Medical Service Corps, he served as a senior administrator in a 400-bed neurosurgical and spinal wound hospital in Vietnam and earned the Bronze Star for meritorious achievement in ground operations against hostile forces. He was honorably discharged at the rank of captain in December 1969. He was elected mayor of Rapid City in 1971 at the age of 29. During the four years in the position, he led the city’s recovery from the devastating flood of June 1972, dealt with civil unrest associated with American Indian Movement in February 1973, and successfully campaigned for the construction and development of a new civic center. After leaving the mayor’s office in 1975, he was the Democratic nominee for US Senate in 1978 but was defeated in the general election. He worked in real estate development and as a cable television entrepreneur. He also served as the senior vice president and national marketing director for a golf course development firm.

In his first year as mayor, Don married JoAnn Baumann. The couple raised two daughters, D’Anna and Debra before JoAnn passed away in 2010. He currently resides in Littleton, Colorado.