Anyway, I had to google thee historical violent crime data myself. Turns out neither of you are being entirely honest. GP is definitely wrong when he asserts that crime has skyrocketed from "three decades ago". Would have been late 80s, early 90s and historical data says crime was much higher at that time. (Multiple times higher actually. So "jostmey" was not a little off, but way off on that assertion according to data.)
And you're not being entirely honest when you say demographics have changed and imply that means a change in crime rates. At least, the rate of decrease of violent crime has gone nowhere over the past 30 years or so. It's decreasing at the same rate today, as it was in 2009, and in 1999. Meanwhile, demographic rate of change was near constant until it ratcheted up around 2008 apparently. (And then only in downtown, and only in the income dimension. Not racially.) So, following your implication, the rate of decline in, say, violent crime, should have ratcheted up around that time as well.
The really interesting thing though is that even if I had validated either of your assertions in the data, neither of your explanations shed much light on plausible reasons for the disparity the article mentions. It's like you two just took your preferred world views and started arguing with each other without regard to what the data actually stated, or even what the original question actually was.
I mean, OK, we get it. You like Chicago. Fine. Just say that and leave it at that, don't try to snow us.
Same with "jostmey". We get it. You don't like Chicago. Just say that and leave it there. Why try to blow smoke up our collective rears?