Crest Hill, IL has a population of 20,316 and is the 2,141st largest city in the United States. The population density is 2,231 per sq mi which is 904% higher than the Illinois average and 2363% higher than the national average. The median age in Crest Hill is 37 which is approximately equal to the Illinois average of 37. In Crest Hill, 48% of the population over 15 years of age are married, 79% speak English and 14% speak Spanish. 77% of Crest Hill residents were born in Illinois, 11% were born out of state, 1% were born outside of the United States and 11% were foreign born.