Lenzburg is located in St. clair county Illinois with a geographic area of 1.2 square miles. The total population in Lenzburg is 411 with 47.2% male and 52.8% female. Children under age 5 represent 4.9% of the population, under age 18 equal 22.1% of the population and over age 65 is 15.1% of the population. The median household income is $40,000, per capita income is $22,876. There are a total of 176 housing units with 79.0% owner occupied. Education includes 54.5% of residents that are high school graduates and 9.1% with a bachelor's degree or higher. The average temperature in Lenzburg in the summer is 74 degrees, and in the winter 27 degrees.