The Pierce County terrain consists of low rolling hills, sloping to the east and southeast. The north fork of the Elkhorn River flows southeastward through the central part of the county, while Dry Fork drains the lower western part, then discharges into the north fork of the Elkhorn. Most of the county's area is devoted to agriculture, often under central pivot irrigation. The county has a total area of, of which is land and is water.
As of the 2000 United States Census, there were 7,857 people, 2,979 households, and 2,141 families in the county. The population density was 14 people per square mile. There were 3,247 housing units at an average density of 6 per square mile. The racial makeup of the county was 98.65% White, 0.08% Black or African American, 0.36% Native American, 0.20% Asian, 0.03% Pacific Islander, 0.23% from other races, and 0.46% from two or more races. 0.71% of the population were Hispanic or Latino of any race. There were 2,979 households out of which 35.30% had children under the age of 18 living with them, 63.40% were married couplesliving together, 5.70% had a female householder with no husband present, and 28.10% were non-families. 25.70% of all households were made up of individuals and 13.70% had someone living alone who was 65 years of age or older. The average household size was 2.59 and the average family size was 3.14. The county population contained 29.00% under the age of 18, 7.00% from 18 to 24, 26.00% from 25 to 44, 20.90% from 45 to 64, and 17.20% who were 65 years of age or older. The median age was 38 years. For every 100 females, there were 100.00 males. For every 100 females age 18 and over, there were 95.10 males. The median income for a household in the county was $32,239, and the median income for a family was $40,500. Males had a median income of $26,563 versus $20,237 for females. The per capita income for the county was $15,980. About 8.80% of families and 11.80% of the population were below the poverty line, including 14.20% of those under age 18 and 12.90% of those age 65 or over.
Pierce County voters have been reliably Republican for decades. In no national election since 1936 has the county selected the Democratic Party candidate.