McHenry is a city in McHenry County, Illinois, United States. The 2010 U.S. census reported its population at 26,992 and rests at an elevation of 797 feet. McHenry was at one time the county seat of McHenry County, which once included adjoining Lake County to the east. McHenry took its name from McHenry County, which was named for Major William McHenry, a prominent officer in the Black Hawk War.
McHenry is located 50 miles northwest of Chicago in northeastern Illinois on the Fox River. According to the 2010 census, McHenry has a total area of 15.175 square miles (39.30 km), of which 14.74 square miles (38.18 km) (or 97.13%) is land and 0.435 square miles (1.13 km) (or 2.87%) is water. McHenry lies within the Fox River Valley, and its downtown area is situated on that river which is how it earned the nickname “The Heart of the Fox River”.
The population density was 1,850.2 per square mile (714.4/km²). There were 8,127 housing units at an average density of 699.4 per square mile (270.0/km²). The racial makeup of the city was 94.18% White, 0.35% African American, 0.21% Native American, 0.89% Asian, 0.04% Pacific Islander, 3.31% from other races, and 1.02% from two or more races. Hispanic or Latino people of any race were 7.10% of the population.
There were 7,872 households of which 38.7% had children under the age of 18 living with them, 57.2% were married couples living together, 9.7% had a female householder with no husband present, and 29.4% were non-families. 24.7% of all households were made up of individuals and 9.9% had someone living alone who was 65 years of age or older. The average household size was 2.70 and the average family size was 3.25.
Age distribution was 28.5% under the age of 18, 7.8% from 18 to 24, 32.7% from 25 to 44, 19.9% from 45 to 64, and 11.0% who were 65 years of age or older. The median age was 34 years. For every 100 females, there were 94.8 males. For every 100 females age 18 and over, there were 91.2 males.
The median household income was $55,759, and the median family income was $66,040. Males had a median income of $46,552 versus $29,808 for females. The per capita income for the city was $23,272. About 3.8% of families and 4.6% of the population were below the poverty line, including 6.1% of those under age 18 and 2.6% of those age 65 or over.