In 1947, Southern and his Father each invested $2,000 in the original Alberta Trailer Hire Co., which later became ATCO. Southern received a bachelor of science degree from the University of Alberta in 1953 and began to work full-time for the company. As of 2007 the Southern family is still in control of ATCO. He passed the title of Chairman, President and Chief Executive Officer to his daughter, Nancy Southern, in January 2000.