I had never heard of "St. Louis-style" pizza until I read an article about it about ten years ago. I had been eating it for years (but was unaware of the name) from the time I was a child in Northwest Indiana in the 1960s until I moved to Florida in 1990, at which point my access to it completely disappeared. Whenever I return to Hammond, Indiana or Schererville, Indiana, getting some (repeatedly) is a high priority. The place in Hammond, Indiana, which serves it is House of Pizza. I can't remember the name of the place in Schererville, but I understand that it is owned by relatives of the guy who owns the House of Pizza in Hammond.
What I like most about it is the provel cheese, which I have never encountered elsewhere, the slightly bitter green peppers which have been parboiled and then charred, the super crisp crust, and the fact that the makers believe in incorporating basil, oregano, garlic and I don't know what all else, into the tomato sauce. No "here's a bland pizza, now sprinkle it with garlic powder, basil, and oregano at the table" for this restaurant! Everything has flavor, including Italian sausage with a hefty dose of fennel seed!
Anyway, apparently this restaurant is a convert, proselytizing about St. Louis-IMO's-style pizza from St. Louis.