As of the 2000 United States Census,[9] there were 8,807 people, 3,625 households, and 2,494 families in the county.

The racial makeup of the county was 96.18% White, 0.16% Black or African American, 0.50% Native American, 0.17% Asian, 0.02% Pacific Islander, 1.69% from other races, and 1.27% from two or more races.

27.30% of all households were made up of individuals, and 13.20% had someone living alone who was 65 years of age or older.

As of the 2010 United States Census, there were 8,667 people, 3,838 households, and 2,505 families in the county.

[11] The racial makeup of the county was 95.4% white, 0.4% Asian, 0.4% American Indian, 0.3% black or African American, 0.1% Pacific islander, 2.0% from other races, and 1.5% from two or more races.

[10] In terms of ancestry, 45.3% were German, 21.1% were English, 17.3% were Irish, and 6.2% were American.

No candidate in history has ever carried Wyoming without winning Platte County.