 Three years later, as Alderman, Mackay led the Calgary contingent on its high-spirited and much publicized visit to the 36th Grey Cup held in Toronto, an occasion generally credited with starting the tradition of Grey Cup reverie, where he rode a horse into The Royal York Hotel, a tradition that has continued each time Calgary is in the Grey Cup.In 1949, he was elected Mayor, serving in that capacity for ten years, a period in which the City witnessed tremendous growth.A self-proclaimed civic-booster, Mackay traveled, widely promoting Calgary.