Waterloo is located in Monroe county Illinois with a geographic area of 8.1 square miles. The total population in Waterloo is 10,417 with 47.9% male and 52.1% female. Children under age 5 represent 6.3% of the population, under age 18 equal 20.3% of the population and over age 65 is 21.1% of the population. The median household income is $71,207, per capita income is $35,376. There are a total of 4,318 housing units with 75.0% owner occupied. Education includes 32.0% of residents that are high school graduates and 29.9% with a bachelor's degree or higher. The average temperature in Waterloo in the summer is 76 degrees, and in the winter 27 degrees.
