Lanark is located in Carroll county Illinois with a geographic area of 1.1 square miles. The total population in Lanark is 1,453 with 49.1% male and 50.9% female. Children under age 5 represent 6.3% of the population, under age 18 equal 22.4% of the population and over age 65 is 23.4% of the population. The median household income is $47,917, per capita income is $29,028. There are a total of 617 housing units with 76.0% owner occupied. Education includes 33.7% of residents that are high school graduates and 12.3% with a bachelor's degree or higher. The average temperature in Lanark in the summer is 70 degrees, and in the winter 27 degrees.