Major highways

• Interstate 40
• U.S. Highway 64
• Highway 22
• Highway 23
• Highway 41
• Highway 60
• Highway 96

Adjacent counties

• Madison County (north)
• Johnson County (east)
• Logan County (southeast)
• Sebastian County (southwest)
• Crawford County (west)

National protected area

• Ozark National Forest (part)

2020 census

As of the 2020 United States census, there were 17,097 people, 6,723 households, and 4,537 families residing in the county.

2000 census

As of the 2000 census,^[15] there were 17,771 people, 6,882 households, and 4,961 families residing in the county. The population density was 29 inhabitants per square mile (11/km²). There were 7,673 housing units at an average density of 13 per square mile (5.0/km²). The racial makeup of the county was 96.17% White, 0.62% Black or African American, 0.80% Native American, 0.26% Asian, 0.06% Pacific Islander, 0.74% from other races, and 1.35% from two or more races. 1.74% of the population were Hispanic or Latino of any race.

There were 6,882 households, out of which 32.40% had children under the age of 18 living with them, 59.20% were married couples living together, 8.80% had a female householder with no husband present, and 27.90% were non-families. 24.60% of all households were made up of individuals, and 12.40% had someone living alone who was 65 years of age or older. The average household size was 2.51 and the average family size was 2.99.

In the county, the population was spread out, with 25.80% under the age of 18, 8.50% from 18 to 24, 26.70% from 25 to 44, 23.20% from 45 to 64, and 15.80% who were 65 years of age or older. The median age was 38 years. For every 100 females, there were 98.00 males. For every 100 females age 18 and over, there were 95.80 males.

The median income for a household in the county was $30,848, and the median income for a family was $36,189. Males had a median income of $27,907 versus $18,822 for females. The per capita income for the county was $14,616. About 10.60% of families and 15.20% of the population were below the poverty line, including 16.20% of those under age 18 and 15.70% of those age 65 or over.

Cities

• Altus
• Branch
• Charleston (county seat)
• Ozark (county seat)
• Wiederkehr Village

Town

• Denning

Unincorporated communities

• Alix
• Cecil
• Peanut

Ghost towns

• Sub Rosa

Townships

Townships in Arkansas are the divisions of a county. Each township includes unincorporated areas; some may have incorporated cities or towns within part of their boundaries. Arkansas townships have limited purposes in modern times. However, the United States census does list Arkansas population based on townships (sometimes referred to as "county subdivisions" or "minor civil divisions"). Townships are also of value for historical purposes in terms of genealogical research. Each town or city is within one or more townships in an Arkansas county based on census maps and publications. The townships of Franklin County are listed below; listed in parentheses are the cities, towns, and/or census-designated places that are fully or partially inside the township. ^[17][18][19]