Jacksonville, IA has a population of 32 and is the 28,553rd largest city in the United States. The population density is 325 per sq mi which is 496% higher than the Iowa average and 259% higher than the national average. The median age in Jacksonville is 61 which is approximately 61% higher than the Iowa average of 38. In Jacksonville, 75% of the population over 15 years of age are married, 100% speak English and 0% speak Spanish. 100% of Jacksonville residents were born in Iowa, 0% were born out of state, 0% were born outside of the United States and 0% were foreign born.