Knoxville, IL has a population of 2,793 and is the 9,167th largest city in the United States. The population density is 1,189 per sq mi which is 435% higher than the Illinois average and 1213% higher than the national average. The median age in Knoxville is 45 which is approximately 20% higher than the Illinois average of 37. In Knoxville, 62% of the population over 15 years of age are married, 97% speak English and 2% speak Spanish. 86% of Knoxville residents were born in Illinois, 13% were born out of state, 1% were born outside of the United States and 1% were foreign born.