Clearfield County was created on March 26, 1804, from parts of Huntingdon and Lycoming Counties but was administered as part of Centre County until 1812. Its county seat is Clearfield.
As of the census of 2000, there were 83,382 people, 32,785 households, and 22,916 families residing in the county. The population density was 73 people per square mile (28/km²). There were 37,855 housing units at an average density of 33 per square mile (13/km²). The racial makeup of the county was 97.40% White, 1.49% Black or African American, 0.12% Native American, 0.26% Asian, 0.01% Pacific Islander, 0.26% from other races, and 0.46% from two or more races. 0.56% of the population were Hispanic or Latino of any race. 22.9% were of German, 13.6% American, 10.2% English, 9.9% Irish, 9.1% Italian and 6.0% Polish ancestry according to Census 2000.
There were 32,785 households out of which 29.70% had children under the age of 18 living with them, 56.60% were married couples living together, 9.30% had a female householder with no husband present, and 30.10% were non-families. 26.30% of all households were made up of individuals and 13.10% had someone living alone who was 65 years of age or older. The average household size was 2.44 and the average family size was 2.94.
In the county, the population was spread out with 22.70% under the age of 18, 7.70% from 18 to 24, 28.80% from 25 to 44, 23.90% from 45 to 64, and 16.90% who were 65 years of age or older. The median age was 39 years. For every 100 females there were 99.50 males. For every 100 females age 18 and over, there were 97.50 males.