Plainville, Connecticut  Plainville is a town in Hartford County, Connecticut, United States. The population was 17,716 at the 2010 census. Plainville first was inhabited by Europeans around 1650. By the 1660s the land was incorporated as land for nearby Farmington. In the year 1869, it separated from Farmington due to the distance of the town center and the growth of Plainville downtown due to the installation of the New York, New Haven and Hartford Railroad and the Hartford, Providence, and Fishkill Railroad. According to the United States Census Bureau, the town has a total area of , of which is land and 0.077 square mile (0.2 km2, or 0.72%, is water. The east side of the town is bordered by two prominent peaks of the Metacomet Ridge: Pinnacle Rock and Bradley Mountain. The Metacomet Trail traverses those peaks. As of the census of 2000, there were 17,328 people in 7,385 households, including 4,645 families, in the town. The population density was 1,776.0 people per square mile (685.5/km2). There were 7,707 housing units at an average density of 789.9 per square mile (304.9/km2). The racial makeup of the town was 93.52% White, 2.25% African American, 0.17% Native American, 1.67% Asian, 0.01% Pacific Islander, 1.19% from other races, and 1.19% from two or more races. Hispanic or Latino of any race were 3.57% of the population. Of the 7,385 households 26.3% had children under the age of 18 living with them, 49.4% were married couples living together, 10.0% had a female householder with no husband present, and 37.1% were non-families. 31.5% of households were one person and 10.4% were one person aged 65 or older. The average household size was 2.32 and the average family size was 2.93. The age distribution was 21.2% under the age of 18, 6.7% from 18 to 24, 32.0% from 25 to 44, 24.8% from 45 to 64, and 15.2% 65 or older. The median age was 40 years. For every 100 females, there were 95.4 males. For every 100 females age 18 and over, there were 93.1 males.