Crestwood, IL has a population of 10,989 and is the 3,670th largest city in the United States. The population density is 3,606 per sq mi which is 1522% higher than the Illinois average and 3880% higher than the national average. The median age in Crestwood is 47 which is approximately 26% higher than the Illinois average of 37. In Crestwood, 53% of the population over 15 years of age are married, 90% speak English and 5% speak Spanish. 82% of Crestwood residents were born in Illinois, 11% were born out of state, 0% were born outside of the United States and 7% were foreign born.