Also, I live in the Chicagoland area and you are 100% right in that having Indiana so close is a big contributor. Most of the biggest gang areas of the city are closer to Indiana than downtown Chicago. They have gun shows in the Indiana cities along the border and the background checks/gun laws for guns shows and private sales in Indiana is VERY lax. I believe I read a statistic from the Chicago police department that more than 40-50% of the guns found in gang possession came from Indiana. We 100% need federal laws for any gun laws to be effective. As far as gang violence goes, people in desperate situations turn to desperate measures. It's a cycle that started with racism and isolation and lack of good education/jobs and turned it into war zone. Those areas of Chicago are almost islands of isolation with limited bus routes/CTA, barely any businesses, grocery stores, restaurants, etc. However, it is almost exactly the same in a way of how these small rust belt/Appalachian areas have become towns of opioid addicted people. The isolation, poor education, and lack of good employment (I would add, not just blue-collar work but work that would keep the educated middle class there too) have made them an island of desperation not dissimilar to the people of the south side of Chicago. How to fix that is really a complex situation (I think even more than gun control issues).
BTW, first and foremost on most political issues, lobbying needs to be curtailed. I was listening to a Fresh Air podcast (NPR) about a guy who started research during the 1980s the climate change issues and had followed it through to now (he wrote a book about what was going on in the 1990s). The amount of (well documented) lobbying and payoff in the late 1980s/1990s by big oil companies was immense to try and change an entire political party to become climate change/environmental impact deniers. Even more interesting is that they paid off a few supposed scientists to publicly cast doubt on the human impact of climate change and journalist ran with it to help make the general public become skeptical of science. The NRA and well as Unions have done similar things.
Seriously, the world is going to hell in a handbasket and I am not sure what will right the train.