Deer Park, IL has a population of 3,409 and is the 8,178th largest city in the United States. The population density is 940 per sq mi which is 323% higher than the Illinois average and 938% higher than the national average. The median age in Deer Park is 44 which is approximately 17% higher than the Illinois average of 37. In Deer Park, 73% of the population over 15 years of age are married, 82% speak English and 2% speak Spanish. 66% of Deer Park residents were born in Illinois, 20% were born out of state, 1% were born outside of the United States and 13% were foreign born.