Many casinos in Oklahoma and Native Tribes have a monopoly on them. The casinos must be located on Tribal land and there is an agreement that no other tribe will build in vicinity of OKC. All this is really on some kind of "hold" because the initial gambling legislation expired this year and Gov. Stitt hired Perkins-Coie (ya those guys) to negotiate an altered arrangement.
Note that the only blank areas are OKC and northwest Oklahoma.
The rest of the state is covered by Tribal jurisdictions.
Some kind of situation going on, eh ?
https://www.ok.gov/health2/documents/map_tribal_jurisdictions.pdf