Coal City, IL has a population of 5,687 and is the 5,955th largest city in the United States. The population density is 1,083 per sq mi which is 387% higher than the Illinois average and 1095% higher than the national average. The median age in Coal City is 35 which is approximately 7% lower than the Illinois average of 37. In Coal City, 61% of the population over 15 years of age are married, 94% speak English and 5% speak Spanish. 85% of Coal City residents were born in Illinois, 13% were born out of state, 1% were born outside of the United States and 1% were foreign born.