Willowbrook CDP, IL has a population of 1,966 and is the 11,117th largest city in the United States. The population density is 590 per sq mi which is 165% higher than the Illinois average and 551% higher than the national average. The median age in Willowbrook CDP is 49 which is approximately 31% higher than the Illinois average of 37. In Willowbrook CDP, 61% of the population over 15 years of age are married, 93% speak English and 2% speak Spanish. 72% of Willowbrook CDP residents were born in Illinois, 25% were born out of state, 0% were born outside of the United States and 3% were foreign born.