Manteno, IL has a population of 8,958 and is the 4,279th largest city in the United States. The population density is 1,798 per sq mi which is 709% higher than the Illinois average and 1884% higher than the national average. The median age in Manteno is 42 which is approximately 12% higher than the Illinois average of 37. In Manteno, 65% of the population over 15 years of age are married, 96% speak English and 2% speak Spanish. 83% of Manteno residents were born in Illinois, 15% were born out of state, 0% were born outside of the United States and 3% were foreign born.