That's news to me. Are you sure you aren't thinking of Sprint since they merged with T-Mobile?
Yep, Chicago was one of the cities I had issues with US Cellular. They are a regional carrier (Iowa is their hotbed) but charge national prices.
We also switched to Verizon (sort of). We have Total Wireless which is a MVNO that uses Verizon towers and we have been nothing but pleased. Verizon national coverage for fraction of what we were paying when with US Cellular. However just this week they announced Verizon is buying Total Wireless' parent company TracPhone. I'm hoping this means the services will be even better. Verizon said they plan to bring 5G so hopefully they won't raise the price too much.