This is an example of a poorly stated question. There are several plains states and they are in the Lower 48. What else the questioner seeks is indecipherable.
Interior plains
The plains are located in several states.
The plains are located in several states.
Within the states
There are actually four states whose boundaries lie entirely in the Great Plains. They are North Dakota, South Dakota, Nebraska, and Kansas.
Several states inhabit the Great Plains in the center of the United States. Some of the states include North Dakota, South Dakota and Nebraska.
West Siberian Plains
plains
s. dakota, nebraska and kansas
The Central Lowlands lie between the Appalachians Highlands Great and the Plains.
rivers
No.
Lesotho and Eswatini are two independent states that lie within South Africa's borders. Both countries are enclaved by South African territory.