Clear Lake, IL has a population of 219 and is the 24,049th largest city in the United States. The population density is 2,055 per sq mi which is 824% higher than the Illinois average and 2168% higher than the national average. The median age in Clear Lake is 54 which is approximately 45% higher than the Illinois average of 37. In Clear Lake, 57% of the population over 15 years of age are married, 98% speak English and 1% speak Spanish. 84% of Clear Lake residents were born in Illinois, 16% were born out of state, 0% were born outside of the United States and 0% were foreign born.