Ellis Mathes spent 40 years working for the State of Idaho and served as its first traffic engineer. As such, he was influential in establishing a strong traffic engineering organization and function in the Idaho Highway Department, as well as in other states.
Since his retirement, he has remained active in transportation planning, serving on the Idaho Board of Engineering Examiners, the Governor's Special Transportation Task Force, the Chamber of Commerce Transportation Committee, and the University of Idaho Engineering Advisory Board.
Mathes has been an active ITE member at the section and district levels, and he is a past president of the Western Section.