Lanark is a city in Carroll County, Illinois, United States. The population was 1,584 at the 2000 census. As of 2005 census estimate, the population decreased to 1,483. Early in the Twentieth Century, it was home to the Cotta steam car company.
Lanark is located at (42.101346, -89.832120).
There were 645 households out of which 31.8% had children under the age of 18 living with them, 57.0% were married couples living together, 9.0% had a female householder with no husband present, and 31.4% were non-families. 27.2% of all households were made up of individuals and 16.0% had someone living alone who was 65 years of age or older. The average household size was 2.43 and the average family size was 2.96.
In the city the population is spread out with 25.6% under the age of 18, 6.3% from 18 to 24, 28.7% from 25 to 44, 21.4% from 45 to 64, and 18.0% who were 65 years of age or older. The median age was 39 years. For every 100 females there were 97.0 males. For every 100 females age 18 and over, there were 88.9 males.
The median income for a household in the city was $35,500, and the median income for a family was $45,800. Males had a median income of $31,705 versus $21,576 for females. The per capita income for the city was $17,518. About 5.6% of families and 8.0% of the population were below the poverty line, including 8.9% of those under age 18 and 6.9% of those age 65 or over.