Plains Court is in the Twentieth judicial district of Montana. SR 200 runs through Plains and is met at the Southern end of town by SR 28.

Since Plains in an open, protected pasture; it was used by the Indians as a wintering place for them and their horses and was called "Horse Plains". Later on stockmen, attracted by these characteristics of the area, brought their horses from as far away as the state of Washington. Even wild horses would gather here to escape the snows. When a post office was established here around 1883, the name of the area was changed to Plains. The annual Sanders County fair is held at the fairgrounds in this city at the end of August. A Professional Rodeo Cowboys association rodeo and Demolition derby are held as a part of this fair.