Northwest Harwinton is a census-designated place (CDP) in the town of Harwinton in Litchfield County, Connecticut, United States. The population was 3,242 at the 2000 census. The CDP is generally the area west of Harmony Hill Road and Plymouth Road, and north of Delay Road. The CDP contains the town center.
According to the United States Census Bureau, the CDP has a total area of 22.8 km² (8.8 mi²). 22.5 km² (8.7 mi²) of it is land and 0.3 km² (0.1 mi²) of it (1.14%) is water.
As of the census of 2000, there were 3,242 people, 1,255 households, and 953 families residing in the CDP. The population density was 143.9/km² (372.5/mi²). There were 1,296 housing units at an average density of 57.5/km² (148.9/mi²). The racial makeup of the CDP was 98.95% White, 0.06% African American, 0.09% Native American, 0.40% Asian, 0.09% Pacific Islander, 0.15% from other races, and 0.25% from two or more races. Hispanic or Latino of any race were 0.99% of the population.
There were 1,255 households out of which 31.2% had children under the age of 18 living with them, 67.6% were married couples living together, 5.5% had a female householder with no husband present, and 24.0% were non-families. 20.1% of all households were made up of individuals and 9.9% had someone living alone who was 65 years of age or older. The average household size was 2.58 and the average family size was 2.99.
In the CDP the population was spread out with 24.5% under the age of 18, 4.5% from 18 to 24, 27.7% from 25 to 44, 28.2% from 45 to 64, and 15.1% who were 65 years of age or older. The median age was 42 years. For every 100 females there were 99.8 males. For every 100 females age 18 and over, there were 96.7 males.
The median income for a household in the CDP was $58,295, and the median income for a family was $65,795. Males had a median income of $47,083 versus $40,161 for females. The per capita income for the CDP was $26,508. About 1.4% of families and 2.9% of the population were below the poverty line, including none of those under age 18 and 3.4% of those age 65 or over.