Bentley, IL has a population of 20 and is the 28,788th largest city in the United States. The population density is 140 per sq mi which is 37% lower than the Illinois average and 54% higher than the national average. The median age in Bentley is 53 which is approximately 40% higher than the Illinois average of 37. In Bentley, 30% of the population over 15 years of age are married, 100% speak English and 0% speak Spanish. 85% of Bentley residents were born in Illinois, 15% were born out of state, 0% were born outside of the United States and 0% were foreign born.