City rivalries?

[Franknburger]

There exist a number of established rivalries between larger cities, and I am curious about how they have developed and are maintained.
First a delineation: I don't mean the traditional national anti-Capital sentiment, nor the arrogance of a larger city vis-à-vis a smaller suburb. I also don't mean a rivalry that is only based on sports (the Schalke-Dortmund type for those of you acquainted with German soccer), though sports of course is one of the mechanisms to maintain such a rivalry.

Let's start with a few German examples:
1. Run for No.2: Hamburg-Munich (of course enhanced by religion, geographic and cultural distance, etc.)
2. Economic vs. political regional centre: Leipzig-Dresden, Lübeck-Kiel
3. Historical discrimination (that's an interesting pattern I only came across after some research): Cologne-Düsseldorf. Cologne used to have the trade monopoly on the Rhine, meaning trade ships by-passed nearby Düsseldorf. When industrialisation set in, however, Düsseldorf took over. Moreover, when Prussia gained possession of the Rhineland, they selected Düsseldorf as provincial capital, deeply hurting Cologne's pride (Roman founding, largest German city throughout the middle-ages).

So, what city rivalries exist in your country/state? How have they developed?

[Franknburger]

Oslo vs the rest of Norway

Does not count. Nobody likes capitals (Paris vs. rest of France, Rome vs. rest of Italy, Athens vs. rest of Greece etc.), while the capitals don't care.
What about Bergen-Trondheim?

New York is above considering any American city its worthy rival. 

Even not L.A.? Otherwise, I suggest for the purpose of this thread to declare NYC the unofficial capital of the USA, which means it is out...

Memphis v Nashville. Same state, different worlds. Memphis is ghetto Deep South blues. Nashville is white trash Country rhinestones. They're growing way faster and they can have it. I don't want to be the next Atlanta. We're in the Goldilocks zone for size, as far as I'm concerned.

That sounds interesting, and thrills the musician in me. Tell us more! Do you have "Nashville jokes" in Memphis? Band battles? Competing events aside from sports (like the Cologne-Düsseldorf carnival rivalry)? Does the rivalry reflect on state politics?

Stephenville vs. Brownwood
Midland v Odessa
Texas City v Lamarque

I must confess I am neither familiar with Stephenville, nor Brownwood, nor Texas City, nor Lamarque. Nevertheless, Midland-Odessa sounds quite interesting and makes me curious about more details.

A few more cases that caught my attention and interest, because they were new to me, and/or might provide interesting case studies:

Alberta-Edmonton
Rochester vs. Buffalo
St. Louis vs. Kansas City
Philadelphia vs. Pittsburgh
Cleveland vs. Cincinnati
Houston vs. Dallas
Seattle vs. Portland

.. and of course
Karlsruhe/Mannheim (first time I have ever heard of it)