Fairview Heights, IL has a population of 16,793 and is the 2,546th largest city in the United States. The population density is 1,470 per sq mi which is 561% higher than the Illinois average and 1522% higher than the national average. The median age in Fairview Heights is 40 which is approximately 7% higher than the Illinois average of 37. In Fairview Heights, 56% of the population over 15 years of age are married, 93% speak English and 3% speak Spanish. 59% of Fairview Heights residents were born in Illinois, 36% were born out of state, 1% were born outside of the United States and 4% were foreign born.