Brooklyn, IL has a population of 740 and is the 17,120th largest city in the United States. The population density is 890 per sq mi which is 300% higher than the Illinois average and 883% higher than the national average. The median age in Brooklyn is 27 which is approximately 29% lower than the Illinois average of 37. In Brooklyn, 26% of the population over 15 years of age are married, 100% speak English and 0% speak Spanish. 68% of Brooklyn residents were born in Illinois, 32% were born out of state, 0% were born outside of the United States and 0% were foreign born.