Sullivan is a city located in Sullivan County Indiana. It is also the county seat of Sullivan County. With a 2020 population of 4,115, it is the 139th largest city in Indiana and the 5323rd largest city in the United States . Sullivan is currently growing at a rate of 0.27% annually but its population has decreased by -3.15% since the most recent census, which recorded a population of 4,249 in 2010. Sullivan reached it's highest population of 5,423 in 1950. Spanning over 2 miles, Sullivan has a population density of 2,194 people per square mile.
The average household income in Sullivan is $44,426 with a poverty rate of 15.81%. The median rental costs in recent years comes to $616 per month, and the median house value is $73,700. The median age in Sullivan is 41.7 years, 38.1 years for males, and 48.2 years for females.