Born in Moose Jaw, Saskatchewan, McCaig dropped out of high school to become a truck driver, following in the footsteps of his father, John W. (Jack) McCaig, for whom he worked in the Maccam Transport Company.
In 1961, the company moved to Calgary and bought a competing company named H.M. Trimble & Sons, thus expanding their business into the rest of Alberta, and into British Columbia and Alaska. The merged company is known as Trimac for "Tri"mble and "Mac"cam as well for John and his three "Mac" brothers. McCaig served as its CEO until his retirement in 1994, and later became chairman of the board.
- Foran, Max (1982). Calgary, Canada's frontier metropolis : an illustrated history. Windsor Publications. p. 355. ISBN 0-89781-055-4.