Green Oaks, IL has a population of 3,832 and is the 7,637th largest city in the United States. The population density is 967 per sq mi which is 335% higher than the Illinois average and 967% higher than the national average. The median age in Green Oaks is 44 which is approximately 18% higher than the Illinois average of 37. In Green Oaks, 72% of the population over 15 years of age are married, 87% speak English and 1% speak Spanish. 65% of Green Oaks residents were born in Illinois, 24% were born out of state, 1% were born outside of the United States and 10% were foreign born.