Sullivan is located in Sullivan county Indiana with a geographic area of 1.9 square miles. The total population in Sullivan is 4,081 with 48.4% male and 51.6% female. Children under age 5 represent 7.6% of the population, under age 18 equal 22.6% of the population and over age 65 is 19.8% of the population. The median household income is $35,167, per capita income is $20,885. There are a total of 1,806 housing units with 66.9% owner occupied. Education includes 44.4% of residents that are high school graduates and 9.1% with a bachelor's degree or higher. The average temperature in Sullivan in the summer is 73 degrees, and in the winter 29 degrees.