[3] In the Nebraska license plate system, Keya Paha County is represented by the prefix 82 (it had the 82nd-largest number of vehicles registered by county in the state when the license plate system was established in 1922).

The name "Keya Paha" is taken from the Dakota language; literally translated, it means "turtle hill".

The Dakota name for a set of small hills was given to the county and to the Keya Paha River, which runs through it.

[4] All land north of the Keya Paha River (which includes a small portion of Keya Paha County and most of neighboring Boyd County) was not originally part of Nebraska at the time of statehood, but was transferred from Dakota Territory in 1882.

[5] Keya Paha County lies on the northern boundary of Nebraska, abutting the state of South Dakota.

The county's terrain consists of low rolling hills, whose level areas are used for agriculture, including center pivot irrigation.