Chadwick is a village in Carroll County, Illinois, United States. The population was 551 at the 2010 census, up from 505 in 2000.
According to the 2010 census, Chadwick has a total area of 0.31 square miles (0.80 km), all land. Chadwick is located at 42°0′51″N 89°53′21″W / 42.01417°N 89.88917°W / 42.01417; -89.88917 (42.014081, -89.889078).
As of the census of 2000, there were 505 people, 210 households, and 150 families residing in the village. The population density was 1,595.5 people per square mile (609.3/km²). There were 228 housing units at an average density of 720.3 per square mile (275.1/km²). The racial makeup of the village was 98.22% White, 0.20% Asian, 0.79% from other races, and 0.79% from two or more races. Hispanic or Latino of any race were 0.99% of the population.
There were 210 households out of which 32.9% had children under the age of 18 living with them, 61.0% were married couples living together, 6.2% had a female householder with no husband present, and 28.1% were non-families. 26.2% of all households were made up of individuals and 17.1% had someone living alone who was 65 years of age or older. The average household size was 2.40 and the average family size was 2.86.
In the village, the population was spread out with 24.2% under the age of 18, 7.5% from 18 to 24, 24.4% from 25 to 44, 23.2% from 45 to 64, and 20.8% who were 65 years of age or older. The median age was 40 years. For every 100 females, there were 97.3 males. For every 100 females age 18 and over, there were 96.4 males.
The median income for a household in the village was $39,583, and the median income for a family was $44,773. Males had a median income of $31,250 versus $23,594 for females. The per capita income for the village was $16,617. About 10.4% of families and 10.9% of the population were below the poverty line, including 16.8% of those under age 18 and 8.9% of those age 65 or over.