Franklin County is part of the Frankfort Micropolitan Statistical Area.
As of the census of 2000, there were 47,687 people, 19,907 households, and 12,840 families residing in the county. The population density was 227 people per square mile (87/km²). There were 21,409 housing units at an average density of 102 per square mile (39/km²). The racial makeup of the county was 87.98% White, 9.36% Black or African American, 0.13% Native American, 0.72% Asian, 0.02% Pacific Islander, 0.55% from other races, and 1.24% from two or more races. 1.11% of the population were Hispanic or Latino of any race.
There were 19,907 households out of which 29.50% had children under the age of 18 living with them, 48.70% were married couples living together, 12.20% had a female householder with no husband present, and 35.50% were non-families. 30.40% of all households were made up of individuals and 10.60% had someone living alone who was 65 years of age or older. The average household size was 2.30 and the average family size was 2.86.
In the county the population was spread out with 22.60% under the age of 18, 9.70% from 18 to 24, 30.50% from 25 to 44, 24.90% from 45 to 64, and 12.30% who were 65 years of age or older. The median age was 37 years. For every 100 females there were 93.70 males. For every 100 females age 18 and over, there were 89.70 males.
The median income for a household in the county was $40,011, and the median income for a family was $51,052. Males had a median income of $32,826 versus $26,201 for females. The per capita income for the county was $21,229. About 6.90% of families and 10.70% of the population were below the poverty line, including 12.80% of those under age 18 and 12.20% of those age 65 or over.