[2] Sioux County is included in the Scottsbluff, NE Micropolitan Statistical Area.

The Niobrara River flows southeastward and eastward through the upper central part of the county.

The county terrain is arid low rolling hills, sloping to the east and southeast.

[3] The terrain is sparsely utilized for agriculture, with some center pivot irrigation used.

The racial makeup of the county was 95.2% White, 1.5% Native American, 0.4% Asian, and 2.4% from two or more races.

As of the 2000 United States Census,[15] there were 1,475 people, 605 households, and 444 families in the county.

23.60% of all households were made up of individuals, and 9.40% had someone living alone who was 65 years of age or older.

In no national election since 1936 has the county selected the Democratic Party candidate.