Here is an extreme CliffsNotes version of Pittsburgh's Good Food Revival Movement (if you want more, talk to Big Burrito executive chef Bill Fuller, and David Bernabo, the man behind Food Systems, a fascinating documentary series about Pittsburgh's food scene):
For a long time, Pittsburgh was a crap food town. For one, you couldn't eat steel. For two, there was no vibrant ethnic scene, just a divide between, as Fuller put it, "really rich people who ate in private clubs, and their workers who cooked at home. Basically there was no middle-class dining."
The '70s brought a little bit of Thai and Indian food, some sushi in the '80s, but it was essentially a burgh of red sauce Italian restaurants, steakhouses, pierogies, and fries on sandwiches/salads. Then Big Burrito restaurant group came through in the '90s and raised the bar with locally sourced food (working with farmers), creatively designed restaurants, and a higher level of service. BB acted like a culinary finishing school/networking center for lots of chefs who went on to open their own places (Justin Severino, Kevin Sousa, etc.).