SE KS, SW MO, and NE OK are the most depressing areas ever. no question, no doubt. I once visited a friend at Pitt State, did not do again.
Pine Ridge, South Dakota (Pine Ridge Indian Reservation)
Everything looks, sounds, smells, (and I would imagine though I did not gather data on these two senses) tastes, and feels like poverty and alcoholism.
Back to Kansas, there have been a lot of references to old and declining mining towns and old and declining oil and gas towns. However the old and declining railroad towns (like Herington) are getting neglected here.
As far as interstate signs go my vote goes to the ones on I-70 wanting you to be sure to stop and visit Liberal while you are on your way to either northern Colorado or central Missouri.