Chicago Heights, IL has a population of 30,349 and is the 1,404th largest city in the United States. The population density is 2,977 per sq mi which is 1239% higher than the Illinois average and 3186% higher than the national average. The median age in Chicago Heights is 34 which is approximately 9% lower than the Illinois average of 37. In Chicago Heights, 44% of the population over 15 years of age are married, 73% speak English and 25% speak Spanish. 75% of Chicago Heights residents were born in Illinois, 13% were born out of state, 1% were born outside of the United States and 11% were foreign born.