I think the way this is applied is probably pretty uniquely St. Louis. That question is asked instead of where are you from. It's not judgemental, but does provide a lot of probable information. In Columbus, you may learn which neighborhood someone lives in early in a conversation with someone you meet. You don't decide whether you like the person based on that information, but you do probably make some generalizations (to be later confirmed or denied). Instead of that, folks from St. Louis ask OTHER ST. LOUISANS what high school they went to. It tells even more than neighborhood, but it's just a common question. I've never asked anyone who wasn't from St. Louis that question, since I wouldn't know anything about their high school. However, it's almost always the second question when I'm not in St. Louis, but I meet someone from St. Louis. For example, a guy who lives on Buttles is from St. Louis, and went to Lindbergh high school, and I learned this the first time I met him.
I'm not sure if the reference to size is maybe thinking St. Louis is small. 100 years ago, St. Louis was the 4th largest city in the US. It's just, St. Louis went the direction of sprawl in a shocking way. If you drive from the riverfront in downtown, and stay on highway 70, you will drive through 3 counties of continuous development. It's like if the suburbs of Columbus continued to Dayton. This may be why I think the high school question will probably die out of the culture of younger generations...
Like any city large or small, there are a large number of very specific cultural quirks to natives. St. Louisans can often differentiate which region a person is from by the way they talk (I used to have a west county accent). Natives pronounce "or" as "ar": so we say "highway farty-four" without so much as a smirk or giggle :) And lots of other fun bits that give us identity. The trick is to enjoy these local customs, without making outsiders feel, well, like outsiders.
Chris (Parkway North)
PS: I love Columbus every bit as much as St. Louis -- and am just as big a pain talking about the cool things about Columbus to St. Louisans as I am when talking about St. Louis to others ;) It just seems my old stomping grounds have been mentioned on CU a lot lately...