Marengo is located in Boone county Illinois with a geographic area of 8.5 square miles. The total population in Marengo is 7,871 with 48.0% male and 52.0% female. Children under age 5 represent 8.9% of the population, under age 18 equal 26.5% of the population and over age 65 is 14.9% of the population. The median household income is $69,688, per capita income is $30,626. There are a total of 2,974 housing units with 63.2% owner occupied. Education includes 35.7% of residents that are high school graduates and 18.0% with a bachelor's degree or higher. The average temperature in Marengo in the summer is 71 degrees, and in the winter 27 degrees.