The Platte River flows eastward along the south line of Platte County. The Loup River also flows eastward and east-southeastward through the lower section of the county, discharging into the Platte River near Columbus. The Platte County terrain consists of low rolling hills, largely devoted to agriculture, sloping to the east-southeast. The county has an area of, of which is land and is water.
As of the 2000 United States Census, there were 31,662 people, 12,076 households, and 8,465 families in the county. The population density was 47 people per square mile. There were 12,916 housing units at an average density of 19 per square mile. The racial makeup of the county was 94.29% White, 0.35% Black or African American, 0.28% Native American, 0.40% Asian, 0.03% Pacific Islander, 3.49% from other races, and 1.15% from two or more races. 6.54% of the population were Hispanic or Latino of any race. There were 12,076 households out of which 36.10% had children under the age of 18 living with them, 59.20% were married couplesliving together, 7.60% had a female householder with no husband present, and 29.90% were non-families. 25.90% of all households were made up of individuals and 11.40% 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, 8.10% from 18 to 24, 27.50% from 25 to 44, 21.60% from 45 to 64, and 13.80% who were 65 years of age or older. The median age was 36 years. For every 100 females there were 98.40 males. For every 100 females age 18 and over, there were 95.60 males. The median income for a household in the county was $39,359, and the median income for a family was $47,776. Males had a median income of $30,672 versus $21,842 for females. The per capita income for the county was $18,064. About 5.40% of families and 7.70% of the population were below the poverty line, including 9.00% of those under age 18 and 6.80% of those age 65 or over.
Platte County voters have been reliably Republican for decades. In only one election since 1936 has the county selected the Democratic Party candidate.
