The Greenville Micropolitan Statistical Area includes all of Darke County.
2000 53,309 1990 53,619 1980 55,096 1970 49,141 1960 45,612 1950 41,799 1940 38,831 1930 38,009 1920 42,911 1910 42,933 1900 42,532 1890 42,961 1880 40,496 1870 32,278 1860 26,009 1850 20,276 1840 13,282 1830 6,204 1820 3,622
As of the census of 2000, there were 53,309 people, 20,419 households, and 14,905 families residing in the county. The population density was 89 people per square mile (34/km²). There were 21,583 housing units at an average density of 36 per square mile (14/km²). The racial makeup of the county was 98.09% White, 0.39% Black or African American, 0.17% Native American, 0.25% Asian, 0.02% Pacific Islander, 0.34% from other races, and 0.74% from two or more races. 0.86% of the population were Hispanic or Latino of any race. 43.1% were of German, 20.1% American, 8.1% English, 6.8% Irish and 5.8% French ancestry according to Census 2000.
There were 20,419 households out of which 33.30% had children under the age of 18 living with them, 61.00% were married couples living together, 8.00% had a female householder with no husband present, and 27.00% were non-families. 23.50% of all households were made up of individuals and 11.00% had someone living alone who was 65 years of age or older. The average household size was 2.56 and the average family size was 3.03.
In the county the population was spread out with 26.30% under the age of 18, 7.80% from 18 to 24, 27.50% from 25 to 44, 23.20% from 45 to 64, and 15.30% who were 65 years of age or older. The median age was 37 years. For every 100 females there were 96.10 males. For every 100 females age 18 and over, there were 93.30 males.
The median income for a household in the county was $39,307, and the median income for a family was $45,735. Males had a median income of $32,933 versus $23,339 for females. The per capita income for the county was $18,670. About 6.00% of families and 8.00% of the population were below the poverty line, including 10.10% of those under age 18 and 9.20% of those age 65 or over.