Lake county is located in Illinois with a geographic area of 1,367.9 square miles. The total population in Lake county is 699,682 with 50.0% male and 50.0% female. Children under age 5 represent 5.7% of the population, under age 18 equal 24.2% of the population and over age 65 is 14.3% of the population. The median household income is $92,654, per capita income is $47,223. There are a total of 248,684 housing units with 73.5% owner occupied. Education includes 18.4% of residents that are high school graduates and 48.0% with a bachelor's degree or higher. The average temperature in Lake county in the summer is 70 degrees, and in the winter 24 degrees.