McHenry County, Illinois Demographics 2026

Population Overview

McHenry County is located in Illinois with a total population of 312,591. It is the 6th most populous county out of 102 in Illinois. The county encompasses 30 Census-designated places.

Age Demographics

The median age in McHenry County is 40.7 years. This is 4% higher than the state median of 39.0 years.

Economy, Income & Housing

The median household income in McHenry County is $104,802. This is 26% higher than the state median of $83,390. It is also 30% higher than the national median of $80,734. The poverty rate stands at 6.2%. This is 47% lower than the state poverty rate of 11.8%. The unemployment rate is 4.7%. This is 20% lower than the state rate of 5.8%. The median home value is $308,100. Housing costs are 17% higher than the state median of $263,300. With a home-value-to-income ratio of just 2.9x, McHenry County is one of the most affordable housing markets in the area. 82.7% of occupied housing units are owner-occupied. This homeownership rate is 23% higher than the state average of 67.1%.

Race & Ethnicity

The largest racial or ethnic group in McHenry County is White (non-Hispanic), making up 76.1% of the population. Hispanic or Latino residents account for 16.1%. The Black or African American population (1.4%) is well below the state average of 13.3%.

Education

35.2% of residents aged 25 and older hold a bachelor's degree or higher. This is 7% lower than the state rate of 37.9%. Nationally, 35.7% of adults hold at least a bachelor's degree. The high school graduation rate (or equivalent) is 93.7%.

Data Sources & Methodology

All figures for McHenry County come from the U.S. Census Bureau's American Community Survey (ACS) 2020–2024 5-Year Estimates, with comparisons drawn against Illinois and national averages from the same dataset. See our methodology page for how each metric is defined, or data.census.gov for official tables with margins of error.