Henry is located in Marshall county Illinois with a geographic area of 1.8 square miles. The total population in Henry is 2,352 with 49.4% male and 50.6% female. Children under age 5 represent 6.0% of the population, under age 18 equal 21.3% of the population and over age 65 is 22.7% of the population. The median household income is $49,375, per capita income is $25,927. There are a total of 1,025 housing units with 75.3% owner occupied. Education includes 40.7% of residents that are high school graduates and 21.9% with a bachelor's degree or higher. The average temperature in Henry in the summer is 74 degrees, and in the winter 27 degrees.