I hadn't thought of that. St Louis is right on the border with IL and I'm sure thousands of people live in IL but work in Stl. As you say, many cities are right on the border of another State and some are split. Omaha is another, right up against Iowa. It would be impossible unless they intend to basically shut down the country. They're doing that in AUS. Great Reset?
These days nothing would surprise me. You'd think the flyover States' governments would recognize the possibilities and start banding together and making plans to Join or Die.
KC was my first thought. There are over 100 streets that cross State Line Road between Missouri and Kansas. In St. Louis, a large number of my co-workers live in Illinois, and now that our office is moving back downtown, I am certain that even more new hires will come from Illinois.