Long Lake is an unincorporated community and census-designated place (CDP) in Lake County, Illinois, United States. Per the 2020 census, the population was 3,663. Geography The community is in western Lake County and nearly surrounds Long Lake, which drains northwest via Squaw Creek to Fox Lake, part of the Chain O'Lakes of northern Illinois. The CDP is bordered to the northeast by the village of Round Lake Heights and to the east and south by the village of Round Lake Beach. The CDP is primarily in the eastern part of Grant Township, with a smaller portion in the northwest corner of Avon Township, and an area of about one city block in the southwest corner of Lake Villa Township. Illinois Route 134 runs along the southern edge of the CDP, leading west to U.S. Route 12 in the southern part of Fox Lake and southeast through Round Lake Beach to Hainesville. Long Lake is northwest of downtown Chicago. According to the United States Census Bureau, the CDP has a total area of , of which are land and , or 36.72%, are water. Demographics 2020 census Note: the US Census treats Hispanic/Latino as an ethnic category. This table excludes Latinos from the racial categories and assigns them to a separate category. Hispanics/Latinos can be of any race. 2000 Census As of the census of 2000, there were 3,356 people, 1,150 households, and 857 families residing in the CDP. The population density was . There were 1,237 housing units at an average density of . The racial makeup of the CDP was 93.33% White, 0.33% African American, 0.33% Native American, 0.72% Asian, 4.41% from other races, and 0.89% from two or more races. Hispanic or Latino of any race were 11.53% of the population. There were 1,150 households, out of which 40.1% had children under the age of 18 living with them, 59.0% were married couples living together, 10.0% had a female householder with no husband present, and 25.4% were non-families. 18.7% of all households were made up of individuals, and 4.8% had someone living alone who was 65 years of age or older. The average household size was 2.92 and the average family size was 3.33. In the CDP, the population was spread out, with 30.2% under the age of 18, 8.3% from 18 to 24, 35.5% from 25 to 44, 19.3% from 45 to 64, and 6.8% who were