Niles, IL has a population of 29,628 and is the 1,447th largest city in the United States. The population density is 5,068 per sq mi which is 2180% higher than the Illinois average and 5494% higher than the national average. The median age in Niles is 49 which is approximately 30% higher than the Illinois average of 37. In Niles, 62% of the population over 15 years of age are married, 41% speak English and 10% speak Spanish. 51% of Niles residents were born in Illinois, 6% were born out of state, 1% were born outside of the United States and 43% were foreign born.