[TMWNN]

>I guess because Canada only has like... 6 large cities? (1 million+ people)

More than that, if you want to get to the top of your industry, all major companies (and their jobs) are based on Toronto, Montreal, or Vancouver (plus Edmonton and Calgary for oil/gas). In the US, depending on the industry, it's entirely possible to get to the top of your field while living in (say) Denver, Dallas, Orlando, Charlotte, or Las Vegas.

[pcthrowaway]

Natural resource extraction, agriculture, and conservation/forestry aside (because of course those happen outside of the big cities), you have an excellent school in Waterloo for academics at the top of their industry, Ottawa and Victoria (and I'm sure some other cities) for politics, Alberta for a decent film/acting scene, and a few other cities (Gatineau?) for misc government jobs.