> > The only other state(ish) borders that has a major city on a state border and might have as many people crossing would be the states bounding the District of Columbia.
>
> What about Chicago, Illinois? It's just across the border from Gary, Indiana. South Bend and Elkhart aren't too far away. I imagine there's quite a few Hoosiers who cross the border each day to work at jobs in the Windy City. I have no idea how the population numbers would compare, though. I just thought I'd bring it up.

In Bristol, TN,VA, the state line runs down the middle of the main street of a fairly large town.
Just crossing the street is an interstate journey.
You can stand there and watch people swarm across the state line every time the lights change. I don't recommend that you stand there very long because it will soon become boring.
Howard