Olympia Fields, IL has a population of 4,888 and is the 6,578th largest city in the United States. The population density is 1,663 per sq mi which is 648% higher than the Illinois average and 1736% higher than the national average. The median age in Olympia Fields is 53 which is approximately 43% higher than the Illinois average of 37. In Olympia Fields, 64% of the population over 15 years of age are married, 94% speak English and 1% speak Spanish. 70% of Olympia Fields residents were born in Illinois, 26% were born out of state, 0% were born outside of the United States and 4% were foreign born.