Maddox was the third generation in a family that has built golf courses since the late 1800's. He joined his father's firm in 1924, and was responsible for the development of many of the machines used to build golf courses, from horse and mule drawn, to the use of old army tankers after World War I, through the first steam tractors and giant earth movers of today. Jumbo, along with his father, built the first wooden bulldozer to push dirt over peat fairways in the early 1920's. A disciple of renowned golf course architect Robert Bruce Harris, Maddox also created some notable layouts of his own. In all Maddox constructed or reconstructed over 40 golf courses throughout Illinois, including such notable layouts as Silver Lake Golf Course, River Forest Country Club, Stonehenge Golf Club and Forest Hills Country Club in Rockford.