Chicago and Milwaukee are about as similar as you can get, but they also represent the problem with the question at hand. Unless two cities grew up literally right next to each other at the same time, with similar geographies, demographics, etc. It's quite difficult to draw anything past superficial comparisons between the two.
Denver and Calgary probably get my vote for cities with real geographic and political separation between them. Modern skylines at the border of The Great Plains and Rockies. A history of ranching turned hotspot for young people looking for jobs and an active outdoors lifestyle. Big energy centers transitioning to a more diverse economy. Both in close proximity to some of the best skiing in the world despite being over 1,000 km apart. Both cities like their football and hockey, although the Nuggets are probably a bigger draw in Denver now.
I think 8th Ave in Calgary and the 16th Street Mall in Denver are better comparisons than any of the Toronto or Chicago ones seen so far.
8th ave:
https://www.google.com/maps/@51.0456...2!8i6656?hl=en
16th street:
https://www.google.com/maps/@39.7451...7i13312!8i6656