Crystal Lake is a city located in McHenry County Illinois. With a 2020 population of 39,501, it is the 43rd largest city in Illinois and the 997th largest city in the United States . Crystal Lake is currently declining at a rate of -0.41% annually and its population has decreased by -3.05% since the most recent census, which recorded a population of 40,743 in 2010. Crystal Lake reached it's highest population of 40,766 in 2010. Spanning over 20 miles, Crystal Lake has a population density of 2,091 people per square mile.
The average household income in Crystal Lake is $105,609 with a poverty rate of 6.88%. The median rental costs in recent years comes to $1,274 per month, and the median house value is $221,300. The median age in Crystal Lake is 39.6 years, 38.8 years for males, and 40.2 years for females.