Mercer County, Illinois
Located in Illinois, Mercer County has a population of 15,495 residents and a median age of 44.7 years, making it the #2,126 most populous county out of 3,222 nationwide. In terms of economic indicators, the county has a poverty rate of 8.9%. The median home value is $146,700, and the median household income is $74,182, which is 1% below the national median.
Demographics
Mercer County has a population of 15,495, making it the #2,126 most populous county in the US. The median age is 44.7 years, which is 14.9% above the national median.
Population Trend
Rankings →Year-over-Year Population Growth
Age & Sex Distribution
Race & Ethnicity
Nativity
Geographic Mobility (Past Year)
Economy
The median household income in Mercer County is $74,182, ranking #898 out of 3,222 counties — 1.3% below the national median. The poverty rate is 8.9% and unemployment stands at 3.1%.
Median Household Income Trend
Rankings →Income Distribution
Industry of Employment
Occupation
Housing
The median home value in Mercer County is $146,700 (-48.0% vs national). Renters pay a median of $786/mo and the homeownership rate is 83.8%.
Median Home Value Trend
Rankings →Household Type
Education
In Mercer County, 20.9% of adults age 25+ hold a bachelor's degree or higher, which is 38.0% below the national average, ranking #1,845 out of 3,222 counties.
Bachelor's Degree or Higher Trend
Rankings →Health & Wellbeing
Life expectancy in Mercer County is 77.3 years. 16.6% of adults report poor or fair health and 5.7% lack health insurance. Data from County Health Rankings (2025).
Life Expectancy Trend
Substance Use
16.4% of adults in Mercer County smoke , 36.8% are obese , and 22.3% report excessive drinking.
Adult Smoking Trend
Safety
The suicide rate is 23.9 per 100,000. Motor vehicle deaths occur at a rate of 13.8 per 100,000.
Suicide Rate Trend
Families & Children
13.5% of children in Mercer County live in poverty . The teen birth rate is 15.6 per 1,000 females age 15–19.
Teen Birth Rate Trend
Civic & Transportation
Voter turnout in Mercer County is 73.7%. The mean commute time is 29.9 min, which is 8.2% above the national average.
Voter Turnout Trend
Mean Commute Time Trend
Rankings →Elections
In the 2024 presidential election, Mercer County voted Republican with a margin of 27.1%. The vote was 35.4% Dem / 62.5% Rep. Compared to 2020, the margin shifted 3.1 toward Republicans .
Vote Share Over Time
About Mercer County, Illinois
Mercer County, Illinois has a total population of 15,495, making it the 2,126th most populous county in the United States. The median age in Mercer County is 44.7 years, which is 14.9% above the national median of 38.9 years.
The median household income in Mercer County is $74,182, which ranks #898 of 3,222 counties nationwide. This is 1.3% below the national median of $75,149. The poverty rate is 8.9%, lower than the national rate of 12.6%. The unemployment rate stands at 3.1%.
The median home value in Mercer County is $146,700, 48.0% below the national median. Renters in Mercer County pay a median gross rent of $786 per month. The homeownership rate is 83.8%, compared to the national rate of 64.4%.
In Mercer County, 20.9% of residents aged 25 and older hold a bachelor's degree or higher, 38.0% below the national average of 33.7%. Health insurance coverage stands at 95.4% of the population. The average commute time for workers is 29.9 min.
Mercer County is a diverse community. The largest racial or ethnic group is White (non-Hispanic) at 93.1% of the population, followed by Hispanic or Latino (3.4%) and Two or More Races (2.4%).
All data for Mercer County, Illinois comes from the U.S. Census Bureau's American Community Survey (ACS) 5-Year Estimates. These figures are estimates based on survey sampling and are subject to margin of error. For the most detailed and up-to-date data, visit the Census Bureau's official data portal.