Clark County, Illinois Demographics 2026
Clark County, Illinois has a population of 15,266, the 71st most populous county in Illinois. The median household income is $72,927 and the median home value is $132,400. The poverty rate is 9.2%.
Data vintage: U.S. Census Bureau ACS 2020–2024 5-Year Estimates · refreshed July 2026 · Methodology & source notes
Clark County Quick Facts
How Clark County Changed
Change from the 2019–2023 ACS period to 2020–2024. These are rolling five-year estimates, not year-over-year measurements.
| Metric | 2019–2023 | 2020–2024 | Change |
|---|---|---|---|
| Population | 15,328 | 15,266 | -0.4% |
| Median household income | $70,625 | $72,927 | +3.3% |
| Median home value | $123,100 | $132,400 | +7.6% |
Median Household Income
Median Home Value
Economy & Housing
Household Income Distribution
Detailed income brackets
Employment
Housing Overview
People & Demographics
Age Distribution
Race & Ethnicity
Diversity Index
A less diverse community where one racial or ethnic group represents a large majority.
State average: 61 | National average: 61
Education
Educational Attainment (Adults 25+)
Cities & Places in Clark County
| City | Population | Median Income | Poverty | Home Value |
|---|---|---|---|---|
| Marshall | 4,040 | $76,250 | 6.8% | $118,500 |
| Casey | 2,239 | $48,074 | 12.9% | $91,800 |
| Martinsville | 1,187 | $61,833 | 23.4% | $69,100 |
| Westfield | 415 | $63,819 | 12.3% | $85,600 |
| West Union | 140 | $109,688 | 7.1% | N/A |
Explore Illinois Rankings
Population Overview
Clark County is located in Illinois with a total population of 15,266. It is the 71st most populous county out of 102 in Illinois. The county encompasses 5 Census-designated places.
Age Demographics
The median age in Clark County is 42.6 years. This is 9% higher than the state median of 39.0 years.
Economy, Income & Housing
The median household income in Clark County is $72,927. This is 13% lower than the state median of $83,390. It is also 10% lower than the national median of $80,734. The poverty rate stands at 9.2%. This is 23% lower than the state poverty rate of 11.8%. The unemployment rate is 3.7%. This is 36% lower than the state rate of 5.8%. The median home value is $132,400. Housing costs are 50% lower than the state median of $263,300. With a home-value-to-income ratio of just 1.8x, Clark County is one of the most affordable housing markets in the area. 80.3% of occupied housing units are owner-occupied. This homeownership rate is 20% higher than the state average of 67.1%.
Race & Ethnicity
Clark County has a predominantly White (non-Hispanic) population, comprising 95.0% of all residents. Hispanic or Latino residents account for 1.9%. The White (non-Hispanic) population is significantly higher than the state average (95.0% vs 58.1%). The Black or African American population (0.5%) is well below the state average of 13.3%. The Hispanic or Latino population (1.9%) is well below the state average of 18.8%. The Asian population (0.1%) is well below the state average of 5.9%.
Education
24.9% of residents aged 25 and older hold a bachelor's degree or higher. This is 34% 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 92.5%.
Data Sources & Methodology
All figures for Clark 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.
Frequently Asked Questions
What is the population of Clark County, Illinois?
Clark County has a population of 15,266, making it the 71st most populous county in Illinois.
What is the median income in Clark County?
The median household income in Clark County is $72,927 with a poverty rate of 9.2%.
How many cities are in Clark County, Illinois?
Clark County contains 5 Census-designated places.