Look: I saw this story about St. Louis being the most dangerous city in the United States (suck it, Camden!) and so did all your co-workers. The key to differentiating your patter from everybody else's on the topic is going to be to connect it to some other local story. Second-order references are the key to any successful witticism; you can believe me on this one, because I'm hilarious. So, for purposes of your late-night TV show's monologue: Sports-related Most Dangerous City gags.
↵NFL: "Hey, did you hear St. Louis is the most dangerous city in America? Yeah, uh—you hear about this? Well, for people—I mean, Philadelphia is still the most dangerous city in America for, ah, dogs!" (Optional Norm MacDonald addendum: "Because Michael Vick likes to torture and murder dogs.")
↵"I, ah, saw this on the news today—Kevin, did you see this? St. Louis is the most dangerous city in the entire United States. St. Louis. Of course, this was old news to the St. Louis Rams' defense!"
↵MLB: "So, uh, Albert Pujols was surprised to learn, today, that St. Louis was the scariest city in the United States. Uh, in a related story, Manny Ramirez—he saw it, and he said, 'St. Louis—that's not where I am right now, right?' He was—he was worried about it, you know."
↵"You know, St. Louis was, statistically, the worst place in the United States to be last year if you didn't want to be, you know, mugged. I—somebody mentioned it to Aaron Miles, and he said he'd get right on it."
↵"So it turns out that St. Louis is the most dangerous place in America this year. Of course, this was old news to the St. Louis Cardinals' defense!"
↵NHL: "The St. Louis Blues weren't surprised to learn their hometown was the most dangerous city in the United States (that's the place underneath Canada) in 2010, not at all. In fact—it just explains why their defensemen keep ending up in the hospital!"
↵"This was in the newspaper, ah—it looks like St. Louis is the most dangerous place in America this year. Of course, this was old news to the St. Louis Blues' defense!"
↵NBA: "So the results are in, and it looks like St. Louis was the most dangerous city in America last year. Did you know St. Louis used to have a professional basketball team?"