Hillside, IL has a population of 8,165 and is the 4,625th largest city in the United States. The population density is 2,566 per sq mi which is 1054% higher than the Illinois average and 2732% higher than the national average. The median age in Hillside is 38 which is approximately 2% higher than the Illinois average of 37. In Hillside, 47% of the population over 15 years of age are married, 70% speak English and 27% speak Spanish. 71% of Hillside residents were born in Illinois, 13% were born out of state, 1% were born outside of the United States and 15% were foreign born.