A Mississippi native, Mac Yowell moved to Bowling Green, Kentucky at thirteen years of age. After graduating from the University of Kentucky he began his professional career as an Assistant Resident Engineer. In 1965, Mac left the Department of Highways and spent 27 years in the private sector, working for contractors in Kentucky and Tennessee. In his spare time he taught night courses in the Engineering Technology Department at Western Kentucky University. In 1984 he was named Outstanding Professional Engineer in Construction by the Kentucky Society of Professional Engineers.
In 1992 Mac was appointed State Highway Engineer for the Kentucky Transportation Cabinet, a position he held until 2004. As State Highway Engineer, Mac was responsible for the planning, design, construction, and maintenance of the 27,000 miles of roadways in Kentucky and supervised a workforce of over 5,000.
Mac was the recipient of a Career Achievement Award presented by the UK Civil Engineering Department in 2003. In the Spring of 2004, he was selected for induction into the Hall of Distinction of the College of Engineering at UK.