Liberty, IL has a population of 504 and is the 19,484th largest city in the United States. The population density is 1,331 per sq mi which is 499% higher than the Illinois average and 1369% higher than the national average. The median age in Liberty is 38 which is approximately 2% higher than the Illinois average of 37. In Liberty, 65% of the population over 15 years of age are married, 100% speak English and 0% speak Spanish. 93% of Liberty residents were born in Illinois, 7% were born out of state, 0% were born outside of the United States and 0% were foreign born.