Lake Summerset is a census-designated place (CDP) in Stephenson and Winnebago counties in Illinois. The population was 2,048 at the 2010 census.GeographyLake Summerset is located at .According to the United States Census Bureau, the CDP has a total area of 2.5sqmi, of which 2.1sqmi is land and 0.4sqmi is water.DemographicsAs of the census of 2000, there were 2,061 people, 816 households, and 677 families residing in the CDP. The population density was 995.3 people per square mile (384.4/km²). There were 1,050 housing units at an average density of 507.0/sq mi (195.8/km²). The racial makeup of the CDP was 98.88% White, 0.24% African American, 0.05% Native American, 0.19% Asian, and 0.63% from two or more races. Hispanic or Latino of any race were 0.68% of the population.There were 816 households out of which 25.6% had children under the age of 18 living with them, 77.7% were married couples living together, 3.6% had a female householder with no husband present, and 17.0% were non-families. 13.5% of all households were made up of individuals and 7.6% had someone living alone who was 65 years of age or older. The average household size was 2.53 and the average family size was 2.76.