In 2007 Barren County was named the "Best Place to Live in Rural America" by Progressive Farmer Magazine.
As of the census of 2000, there were 38,033 people, 15,346 households, and 10,941 families residing in the county. The population density was 78 per square mile (30 /km). There were 17,095 housing units at an average density of 35 per square mile (14 /km). The racial makeup of the county was 94.30% White, 4.09% Black or African American, 0.15% Native American, 0.41% Asian, 0.03% Pacific Islander, 0.38% from other races, and 0.65% from two or more races. 0.93% of the population were Hispanic or Latino of any race.
There were 15,346 households out of which 31.70% had children under the age of 18 living with them, 58.30% were married couples living together, 9.80% had a female householder with no husband present, and 28.70% were non-families. 25.60% of all households were made up of individuals and 11.60% 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 2.91.
The age distribution was 24.20% under the age of 18, 8.20% from 18 to 24, 28.80% from 25 to 44, 23.80% from 45 to 64, and 15.00% who were 65 years of age or older. The median age was 38 years. For every 100 females there were 92.70 males. For every 100 females age 18 and over, there were 89.30 males.
The median income for a household in the county was $31,240, and the median income for a family was $37,231. Males had a median income of $29,860 versus $21,208 for females. The per capita income for the county was $16,816. About 11.80% of families and 15.60% of the population were below the poverty line, including 20.30% of those under age 18 and 19.10% of those age 65 or over.
Barren County is served by Interstate 65, which goes through the northwest part of the county, and the Louie B. Nunn Cumberland Parkway, a former toll road that is designated to be part of the future Interstate 66 corridor. U.S. Route 31E, 31W and 68 also pass through the county.
Railroad service is provided by CSX Transportation, whose former Louisville and Nashville Railroad main line passes through Cave City and Park City. The Glasgow Railway Company is a short line which owns a branch from Park City (which was formerly called Glasgow Junction) to Glasgow; the line is serviced via an operating lease by CSX.