Listening to the CBC Today: the Vinyl Cafe from a moving train. Stuart MacLean commented that villages and cities grew up where the train went. That’ it!
In the 1800s, where the train tracks went, that’s where growth went. So cities like Kitchener and Waterloo grew because they had the train tracks and the train stations. A village without the train going through stayed small, even though they had roads going through them. Same idea.
Those areas of the city with rail and rail stations grow and intensify, those with buses and roads, not so much. Bus routes can change, rail much harder to move.