Middletown, IL has a population of 323 and is the 22,072nd largest city in the United States. The population density is 1,346 per sq mi which is 505% higher than the Illinois average and 1386% higher than the national average. The median age in Middletown is 36 which is approximately 5% lower than the Illinois average of 37. In Middletown, 57% of the population over 15 years of age are married, 96% speak English and 0% speak Spanish. 90% of Middletown residents were born in Illinois, 6% were born out of state, 0% were born outside of the United States and 3% were foreign born.