Lake Summerset is a census-designated place (CDP) in Stephenson and Winnebago counties in Illinois. The population was 2,048 at the 2010 census.
Lake Summerset is located at 42°26′58″N 89°23′47″W / 42.44944°N 89.39639°W / 42.44944; -89.39639 (42.449436, -89.396392).
According to the United States Census Bureau, the CDP has a total area of 2.5 square miles (6.5 km), of which 2.1 square miles (5.4 km) is land and 0.4 square miles (1.0 km) (17.20%) is water.
As 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.
In the CDP, the population was spread out with 21.7% under the age of 18, 4.2% from 18 to 24, 22.1% from 25 to 44, 29.8% from 45 to 64, and 22.2% who were 65 years of age or older. The median age was 47 years. For every 100 females, there were 95.7 males. For every 100 females age 18 and over, there were 99.0 males.
The median income for a household in the CDP was $59,648, and the median income for a family was $65,066. Males had a median income of $50,522 versus $27,708 for females. The per capita income for the CDP was $27,160. About 1.0% of families and 0.8% of the population were below the poverty line, including none of those under the age of eighteen or sixty-five or over.