I don't think any other Canadian city would be visible from as far away as Montreal, which has the perfect combination of extremely low-lying, flat surroundings and a 'wall' of perches for viewing 100kms away (Green mountains and maybe even parts of Adirondacks).
I would have figured Calgary was a good candidate, but haven't seen any super-far-away submissions.
Vancouver and surroundings too mountainous.
Toronto best possible distance is across the lake.
A few 100km + examples from elsewhere:
Chicago from 120KMs away in Warren dunes - amazing pic - apparently this is only possible because Chi's highrises are tall enough to 'peak through' the horizon.
Boston, sort of like Montreal, gets some extra distance thanks to the surrounding topography. Here it is from 105KMs away on Mount Monadnock !
Same for San Fran. (115KM away)
And Charlotte (130KM away)
And
(125KMs away)
So far these 5 are the only North American cities where I've found reallllllly long-distance shots.