Lake Zurich, IL has a population of 19,950 and is the 2,181st largest city in the United States. The population density is 2,919 per sq mi which is 1213% higher than the Illinois average and 3122% higher than the national average. The median age in Lake Zurich is 39 which is approximately 4% higher than the Illinois average of 37. In Lake Zurich, 68% of the population over 15 years of age are married, 79% speak English and 6% speak Spanish. 65% of Lake Zurich residents were born in Illinois, 18% were born out of state, 1% were born outside of the United States and 17% were foreign born.