Fox Lake, IL has a population of 10,434 and is the 3,831st largest city in the United States. The population density is 1,340 per sq mi which is 503% higher than the Illinois average and 1379% higher than the national average. The median age in Fox Lake is 43 which is approximately 14% higher than the Illinois average of 37. In Fox Lake, 49% of the population over 15 years of age are married, 88% speak English and 5% speak Spanish. 77% of Fox Lake residents were born in Illinois, 14% were born out of state, 1% were born outside of the United States and 9% were foreign born.