I think it is for all of Canada, and a bit hard to find what I was looking for. But, I was able to access who would appear to be Montreal boot and shoemakers, although as individuals they were listed under boot and shoestores. I did not find my John McMullen as one, on this 1851 directory, though. In 1850 he had been at 15 St Mary Street. There were a number of them on St Mary Street in 1851, and some didn't show the number, so could have been someone else took over his location.
So, now it's seeming somewhat odd that he didn't seem to be there in 1851. Where oh where did my John McMullen go?? Just too many of them!!