Carbondale, IL has a population of 26,066 and is the 1,654th largest city in the United States. The population density is 1,509 per sq mi which is 562% higher than the Illinois average and 1565% higher than the national average. The median age in Carbondale is 24 which is approximately 36% lower than the Illinois average of 37. In Carbondale, 27% of the population over 15 years of age are married, 85% speak English and 5% speak Spanish. 66% of Carbondale residents were born in Illinois, 23% were born out of state, 1% were born outside of the United States and 11% were foreign born.