Naperville, IL has a population of 145,789 and is the 182nd largest city in the United States. The population density is 3,768 per sq mi which is 1595% higher than the Illinois average and 4059% higher than the national average. The median age in Naperville is 39 which is approximately 3% higher than the Illinois average of 37. In Naperville, 66% of the population over 15 years of age are married, 77% speak English and 4% speak Spanish. 55% of Naperville residents were born in Illinois, 25% were born out of state, 1% were born outside of the United States and 19% were foreign born.