Crystal Lake is a city in McHenry County in the U.S. state of Illinois. Named after a lake 1.6 miles (2.6 km) southwest of the city’s downtown, Crystal Lake is 45 miles northwest of Chicago. The population was estimated at 40,036 in July 2018, a 1.8% decrease from 2010. Crystal Lake is the largest city in McHenry County, part of the Chicago metropolitan area.
According to the 2010 census, Crystal Lake has a total area of 18.957 square miles (49.10 km), of which 18.35 square miles (47.53 km) (or 96.8%) is land and 0.607 square miles (1.57 km) (or 3.2%) is water.
As of the 2010 Census, there were 40,743 people, 14,421 households, and 10,551 families living in the city. The population density was 2,220/sq mi (857/km²). There were 15,176 total housing units and 22% of all housing units were in multi-unit structures. The racial makeup of the city was 90.2% White, 1.0% Black or African American, 0.4% Native American, 2.5% Asian, <0.01% Pacific Islander, 4.1% from other races, and 1.8% from two or more races. Hispanic or Latino of any race were 11.7% of the population.
39.2% of the households included children under 18, 58.9% were married couples living together, 10.1% had a female householder with no husband present, and 26.8% were non-families. 22.1% of all households were made up of individuals living alone and 20.3% had someone at least 65 years old living alone. The average household size was 2.81 and the average family size was 3.31.
In the city, the population was spread out with 28.1% under the age of 18, 8.% from 18 to 24, 26.2% from 25 to 44, 27.7% from 45 to 64, and 10.0% who were 65 years of age or older. The median age was 37 years. For every 100 females, there were 97.6 males.
The median income for a household in the city was $78,311, and the median income for a family was $91,870. Males had a median income of $61,982 versus $44,288 for females. The median income for the city was $36,405. About 5.2% of families and 6.2% of the population were below the poverty line, including 9.1% of those under age 18 and 5.3% of those age 65 or over.
In 1990, the population of Latinos (Hispanics) was at 0.1%. Per the 2000 US Census, the Latino population increased to 7% and per the 2010 US Census, the Latino population is now 11.7%.