As of the census of 2000, there were 57,565 people, 22,747 households, and 15,922 families residing in the county. The population density was 85 people per square mile (33/km²). There were 26,904 housing units at an average density of 40 per square mile (15/km²). The racial makeup of the county was 97.64% White, 1.09% Black or African American, 0.18% Native American, 0.23% Asian, 0.02% Pacific Islander, 0.17% from other races, and 0.67% from two or more races. 0.52% of the population were Hispanic or Latino of any race. 33.0% were of German, 12.7% Irish, 12.2% American, 8.6% English, 5.7% Polish and 5.3% Italian ancestry according to Census 2000.
There were 22,747 households out of which 30.40% had children under the age of 18 living with them, 55.80% were married couples living together, 9.90% had a female householder with no husband present, and 30.00% were non-families. 26.20% of all households were made up of individuals and 12.50% had someone living alone who was 65 years of age or older. The average household size was 2.45 and the average family size was 2.93.
In the county, the population was spread out with 24.20% under the age of 18, 7.20% from 18 to 24, 26.70% from 25 to 44, 25.10% from 45 to 64, and 16.80% who were 65 years of age or older. The median age was 40 years. For every 100 females there were 95.40 males. For every 100 females age 18 and over, there were 92.10 males.
In the 2004 United States presidential election, voters registered in Venango County cast 9,024 (38.1%) ballots for Kerry, 14,472 (61.2%) for Bush, and 163 (0.7%) for "other".