I have a great Uncle by the name Fredrick W. MacKay who was born in Cape Breton, Nova Scotia in 1879. We believe that he immigrated to the US after his parents died, probably sometime in the 1920's and is believe to have gone to California, after stops in Boston and Chicago. We've lost the trail after that.
If these photos were taken in 40's this would have put him in his sixties. Please respond if you believe this to be a potential fit.