Marno,
Thanks for your thoughts and welcome. This is my favorite kind of discourse on the board.
It seems that people with a broad range of experiences on both coasts, the South and abroad disagree about the relative prediliction for spice in different regions and cities. Clearly, it isn't as simple as "some people everywhere like spicy food." There's no question that the general populations of New Orleans, Madras, and Guadalajara eat more spicy food than the people of Indianapolis, Oslo and Buenos Aires. I think Chicago's pretty spicy for a US town.
I'll stand by my own personal observation, shared by several people whose insight I admire, that Chicago has more of a taste/tolerance for spicy foods than other places, particularly in the Midwest. I guess if you disagree with the basic premise, then it makes little sense to explore the history behind the alleged general phenomenon. Still, I'd like to figure out where the sport peppers came from (which, by the way, are the shared link to the particulalrly Chicago style of giardiniera). I think it's beyond arguing that Chicago is the only big US city where pickled serrano chiles are a long-time, widely used fast-food condiment. Unlike most of what passed for hot in North America north of the border until very recently, the serranos are spicy under anyone's definition. The rings of bannana peppers found on hot dog carts in Toronto and Italian places back East aren't even close.
Also, Chicago has had a significant Mexican population for much, much longer than 30 years.
To expand the discussion, I'm interested to know what spicy foods were common in the UK and Toronto when you were there, other than Indian, which we have in spades and is, essentially, spicy.
Hot pepper flakes, whether in South Philly, North Beach, or Grand Avenue, are pretty standard stuff at modest Italian restaurants. I think that just goes to the same Italian influence discussed above. But unlike here, where hot dog and beef eaters of every persuasion expect sports and giardiniera as an option (at least), I've never seen mention of hot pepper being an essential or even regular condiment on steaks, hoagies or roast pork sandwiches. If a hot dog or beef stand had no hot peppers here, it would be a basic failure. Not so if the red pepper shaker went missing at a steak place.
I used to spend a lot of time in Philly (and was born there). My love of Tony Luke's is well documeted, yet I would never associate those sandwiches with piquance the way I associate heat with a combo form Johnnie's (where, by the way, as with many Chicago beef stands, the standard (only) sausage is well hotter than what's normal in other Italian American enclaves in the US).
Back to Philly, I will admit to the almost extinct pepper pot soup, which has well-documented links to Afro-Caribbean potages that are nearly identical. That sort of gets to my basic point: I'm not claiming that Chicago is better than some other place, or that something in the water makes its population enjoy serrano peppers. I'm interested in how that came to be.
As for every city having a spicy component, I don't really think so. Where I grew up, Tampa, there is a terrific Latin American and Italian street food tradition, but spicy food was and still is exotic. Recent Mexican and Vietnamese immigration is changing that. But Cuban food very rarely uses hot chiles. Nearly never. Other than a bottle of Crystal at the soul food place or oyster bar, not much is bien picante in Ybor.
PS, I'd add another observation that travel writers and critics from all sorts of places invaribly remark/warn about the heat of the aforementioned fast food condiments. That's because folks generally don't expect searing heat with their fast food.