McHenry County, Illinois Population 2026
Updated April 2026 · US Census ACS 2023 5-Year Estimates · 6th-largest in Illinois
The population of McHenry County, Illinois is 311,366 as of the 2023 American Community Survey, making it the 6th-largest county in Illinois. The median household income is $102,836, the median home value is $286,900, and the median age is 40.4.
The population of McHenry County has grown 2.2% since 2010 (309,121 → 315,959), a +0.16% annualized rate.
311,366
Population
+0.16%
Annual growth
516
People / sq mi
$102,836
Median Income
$286,900
Median Home Value
McHenry County covers 603 sq mi of land at 516.0 people per square mile.
About McHenry County, IL
McHenry County is a county in Illinois with a population of 311,366. It ranks #6 among counties in Illinois by population. The median age is 40.4, older than the national median. The population is 50.1% male and 49.9% female.
The median household income in McHenry County is $102,836, above the US median of $74,580. 4.1% of residents live below the federal poverty level. Home values sit at a median of $286,900, with monthly rent averaging $1,358. The homeownership rate of 82.6% is higher than the national rate of 64.8%.
Educational attainment in McHenry County reflects 35.2% of adults 25 and older holding a bachelor's degree or higher, near the national average of 34.3%. Roughly 14.7% of workers primarily work from home, similar to the national work-from-home rate of 14.2%. The average commute is 30.6 minutes each way.
McHenry County Population History (2010-2024)
The county of McHenry County had a population of 309,121 in 2010 and 315,959 in 2024, a 2.2% growth over 14 years. The peak was 315,959 in 2024. Average annual growth rate: 0.16%.
315,959
Population (2024)
309,121
Population (2010)
315,959
Peak (2024)
0.16%
Avg Annual Growth
| Year | Population |
|---|---|
| 2010 | 309,121 |
| 2011 | 308,519 |
| 2012 | 308,248 |
| 2013 | 307,629 |
| 2014 | 307,425 |
| 2015 | 307,595 |
| 2016 | 307,142 |
| 2017 | 307,842 |
| 2018 | 308,145 |
| 2019 | 307,439 |
| 2020 | 309,973 |
| 2021 | 311,669 |
| 2022 | 311,921 |
| 2023 | 313,435 |
| 2024 | 315,959 |
Race & Ethnicity
| White | 82.4% |
| Black or African American | 1.6% |
| Asian | 0.0% |
| Hispanic or Latino (any race) | 1.2% |
| Two or More Races | 0.0% |
Age & Sex
40.4
Median Age
49.9%
Female
50.1%
Male
15.9%
Age 65+
Age Distribution
Children (under 15): 18.5% · Seniors (65+): 15.9%
Income & Poverty
| Median household income | $102,836+$21,134 vs state |
| Mean household income | $128,231 |
| Per-capita income | $48,275 |
| Poverty rate | 4.1%-4.1% vs state |
| Unemployment rate | 3.3% |
| Employment-to-population | 66.6% |
Top Industries by Employment
The largest employment sector in McHenry County is professional & business services, accounting for 20.2% of workers.
How residents commute
1.4%
Drive alone
1.0%
Carpool
74.9%
Public transit
14.7%
Work from home
30.6 min
Avg commute
Housing
$286,900+$36,400 vs state
Median home value
$1,358
Median rent
82.6%
Homeownership rate
120,605
Total housing units
96.5%
Occupied
3.5%
Vacant
17.4%
Renter-occupied
Social & access
95.3%
With health insurance
97.2%
With broadband internet
16.4%
Foreign-born
5.5%
Veterans (18+)
9.9%
With a disability
84.6%
Speak language other than English at home
Education
93.7%
High School+
35.2%
Bachelor's+
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County rankings
Frequently Asked Questions
McHenry County, Illinois has a population of 311,366 according to the US Census Bureau's 2023 American Community Survey 5-year estimates, making it the 6th-largest county in Illinois. Population density is 516 people per square mile.
The population of McHenry County has grown 2.2% since 2010 (309,121 → 315,959), a +0.16% annualized rate.
The median household income in McHenry County, Illinois is $102,836, with mean (average) household income of $128,231 and per-capita income of $48,275. 4.1% of residents live below the federal poverty level.
In McHenry County, the largest racial and ethnic groups are White (82.4%), Black or African American (1.6%), Hispanic or Latino (1.2%). Figures are from the US Census Bureau's 2023 ACS 5-year estimates and reflect self-reported responses.
The median age in McHenry County, Illinois is 40.4 years. Residents are 49.9% female and 50.1% male.
The median home value in McHenry County is $286,900 and median monthly rent is $1,358. 82.6% of occupied housing units are owner-occupied. The county has 120,605 total housing units, 3.5% of which are vacant.
The largest employment sector in McHenry County, Illinois is professional, scientific, and management services, employing 20.2% of workers. The unemployment rate is 3.3%.
Chicago is among the largest cities associated with McHenry County, Illinois, with a population of 2,707,648.
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Statewide data for Illinois
Population, race, income, age, and trends across Illinois
Data from the American Community Survey (ACS) 5-Year estimates.
Source: U.S. Census Bureau ACS, 2026.