Clear Lake, IA has a population of 7,644 and is the 4,862nd largest city in the United States. The population density is 708 per sq mi which is 1196% higher than the Iowa average and 681% higher than the national average. The median age in Clear Lake is 44 which is approximately 17% higher than the Iowa average of 38. In Clear Lake, 68% of the population over 15 years of age are married, 95% speak English and 3% speak Spanish. 74% of Clear Lake residents were born in Iowa, 24% were born out of state, 0% were born outside of the United States and 3% were foreign born.