I live in Tulsa OK and here reception and data are very good. I have a Samsung S5 with CDMA covered by Sprint.
Headed west along the I-40 down to Flagstaff and not even once I had signal during my trip. Starting probably 100 miles from Oklahoma city the phone kept displaying "Emergency calls only". I checked the coverage map and I do not know whether there is something wrong with my phone or not, but it is not actual. By the way, as soon as I got back, everything started working fine.