Johnsburg is a northwest suburban village in McHenry County, Illinois, United States. The population was 6,337 at the 2010 census.
Johnsburg is located at 42°23′9″N 88°14′9″W / 42.38583°N 88.23583°W / 42.38583; -88.23583 (42.385796, -88.235942).
According to the 2010 census, Johnsburg has a total area of 7.674 square miles (19.88 km), of which 7.08 square miles (18.34 km) (or 92.26%) is land and 0.594 square miles (1.54 km) (or 7.74%) is water. Johnsburg lies within the watershed of the Fox river.
As of the census of 2000, there were 5,391 people, 1,760 households, and 1,501 families residing in the village. The population density was 973.7 people per square mile (375.7/km²). There were 1,875 housing units at an average density of 338.6 per square mile (130.7/km²). The racial makeup of the village was 98.83% White, 0.13% African American, 0.06% Native American, 0.19% Asian, 0.17% from other races, and 0.63% from two or more races. Hispanic or Latino of any race were 1.52% of the population.
There were 1,760 households out of which 44.9% had children under the age of 18 living with them, 73.9% were married couples living together, 7.1% had a female householder with no husband present, and 14.7% were non-families. 11.8% of all households were made up of individuals and 3.9% had someone living alone who was 65 years of age or older. The average household size was 3.06 and the average family size was 3.32.
In the village, the population was spread out with 30.6% under the age of 18, 7.0% from 18 to 24, 28.3% from 25 to 44, 26.4% from 45 to 64, and 7.6% who were 65 years of age or older. The median age was 37 years. For every 100 females, there were 102.1 males. For every 100 females age 18 and over, there were 99.4 males.
The median income for a household in the village was $69,864, and the median income for a family was $73,491. Males had a median income of $51,832 versus $30,893 for females. The per capita income for the village was $27,582. About 1.1% of families and 1.3% of the population were below the poverty line, including 2.1% of those under age 18 and none of those age 65 or over.