St. john is located in Lake county Indiana with a geographic area of 12.6 square miles. The total population in St. john is 18,382 with 49.7% male and 50.3% female. Children under age 5 represent 4.8% of the population, under age 18 equal 22.7% of the population and over age 65 is 19.0% of the population. The median household income is $103,851, per capita income is $46,191. There are a total of 6,787 housing units with 97.6% owner occupied. Education includes 21.6% of residents that are high school graduates and 33.9% with a bachelor's degree or higher. The average temperature in St. john in the summer is 73 degrees, and in the winter 29 degrees.
