Carbon Cliff, IL has a population of 2,024 and is the 10,957th largest city in the United States. The population density is 994 per sq mi which is 347% higher than the Illinois average and 997% higher than the national average. The median age in Carbon Cliff is 32 which is approximately 14% lower than the Illinois average of 37. In Carbon Cliff, 52% of the population over 15 years of age are married, 88% speak English and 3% speak Spanish. 70% of Carbon Cliff residents were born in Illinois, 22% were born out of state, 0% were born outside of the United States and 8% were foreign born.