Mendon is a village in Adams County, Illinois, United States. The population was 953 at the 2010 census. It is part of the Quincy, IL–MO Micropolitan Statistical Area.
Mendon is located at 40°5′18″N 91°17′4″W / 40.08833°N 91.28444°W / 40.08833; -91.28444 (40.088241, -91.284458).
According to the 2010 census, Mendon has a total area of 0.86 square miles (2.23 km), mostly land.
As of the 2000 census, there were 883 people, 348 households, and 238 families residing in the village. The population density was approximately 1,208 people per square mile (467.0/km²). There were 373 housing units at an average density of 510 per square mile (197.3/km²). The racial makeup of the village was 99.66% White, 0.11% African American, 0.11% from other races, and 0.11% from two or more races. Hispanic or Latino of any race were 0.45% of the population.
There were 348 households, of which 34.5% had children under the age of 18 living with them, 55.2% were married couples living together, 10.1% had a female householder with no husband present, and 31.6% were non-families. 26.7% of all households were made up of individuals and 16.7% had someone living alone who was 65 years of age or older. The average household size was 2.5 and the average family size was 3.
In the village, the population was spread out with 27.5% under the age of 18, 9.4% from 18 to 24, 27.4% from 25 to 44, 21.5% from 45 to 64, and 14.2% who were 65 years of age or older. The median age was 35 years. For every 100 females, there were 90 males. For every 100 females age 18 and over, there were 84 males.
The median income for a household in the village was $35,139, and the median income for a family was $41,750. Males had a median income of $30,370 versus $20,000 for females. The per capita income for the village was $15,267. About 6.7% of families and 8.0% of the population were below the poverty line, including 10.0% of those under age 18 and 10.0% of those age 65 or over.