Demographics of Mercer County, Illinois

Mercer County, Illinois had 15,229 people on July 1, 2025, by the Census Bureau’s estimate: −408 since July 2020. Age, income, poverty, housing and origin below come from the American Community Survey, averaged over 2020–2024, each with its margin of error.

Mercer County, in four figures

15,229
Population: July 1, 2025, Vintage 2025 estimate.; −2.6%
Change since July 2020: −408 people.; 44.7 ±0.3
Median age: ACS 2020–⁠2024.; $74,182 ±$7,031
Median household income: ACS 2020–⁠2024, in 2024 dollars.

Population, year by year

July 1 estimates from the Census Bureau’s Vintage 2025. Each year's change is births less deaths, net moves from abroad and net moves from elsewhere in the country, with the Bureau's small residual. The 2020 row's components run 3 months, from the April census to July 1.

Mercer County, Illinois's population shrank 2.6% from July 2020 to July 2025, against +3.1% nationally

The July 1 estimate of Mercer County, Illinois's resident population and the nation's, each year of the Census Bureau's Vintage 2025, as a share of its July 2020 level (= 100).

U.S. Census Bureau — Census Bureau population estimates — counties and Puerto Rico municipios, with components of change

About this chart

The figures

Mercer County, Illinois's population shrank 2.6% from July 2020 to July 2025, against +3.1% nationally. The July 1 estimate of Mercer County, Illinois's resident population and the nation's, each year of the Census Bureau's Vintage 2025, as a share of its July 2020 level (= 100).
July 1	Population	Index	United States
2020	15,637	100.0	100.0
2021	15,587	99.7	100.2
2022	15,511	99.2	100.7
2023	15,472	98.9	101.6
2024	15,292	97.8	102.5
2025	15,229	97.4	103.1

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Population of Mercer County, Illinois on July 1 of each year, Vintage 2025
July 1	Population	Change	Births less deaths	From abroad	From elsewhere in the country
2020	15,637	−64	−13	0	−47
2021	15,587	−50	−88	0	+26
2022	15,511	−76	−107	+1	+40
2023	15,472	−39	−58	+1	+23
2024	15,292	−180	−64	+2	−120
2025	15,229	−63	−51	+2	−13

Age, 2020–2024

The median age is 44.7 ±0.3: for men 44.2 ±0.5 and for women 45.1 ±0.5. Shares are of everyone the survey counts, in the Bureau’s sex-by-age table (B01001).

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People in Mercer County by age, ACS 2020–2024
Age	People	Share	Illinois	United States
Under 5	738 ±25	4.8% ±0.2	5.4% ±<0.1	5.6% ±<0.1
5 to 17	2,492 ±148	16.1% ±1.0	16.4% ±0.1	16.3% ±<0.1
18 to 24	1,142 ±146	7.4% ±0.9	9.1% ±<0.1	9.1% ±<0.1
25 to 44	3,476 ±184	22.4% ±1.2	26.9% ±0.1	26.9% ±<0.1
45 to 64	4,258 ±212	27.5% ±1.4	25.2% ±0.1	24.8% ±<0.1
65 and over	3,389 ±226	21.9% ±1.5	17.0% ±0.1	17.2% ±<0.1

Income and poverty, 2020–2024

Median household income is $74,182 ±$7,031, and income per person $39,391 ±$1,834, in 2024 dollars. The median is $83,390 ±$362 in Illinois and $80,734 ±$166 in the United States.

Households by income

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Households in Mercer County by income, ACS 2020–2024
Household income	Households	Share	Illinois	United States
Under $25,000	929 ±162	14.2% ±2.4	14.6% ±0.1	14.6% ±<0.1
$25,000 to $49,999	1,257 ±194	19.1% ±2.9	16.0% ±0.2	16.7% ±<0.1
$50,000 to $74,999	1,141 ±162	17.4% ±2.4	14.8% ±0.1	15.5% ±<0.1
$75,000 to $99,999	749 ±115	11.4% ±1.7	12.6% ±0.1	12.6% ±<0.1
$100,000 to $149,999	1,341 ±179	20.4% ±2.7	18.0% ±0.2	17.5% ±<0.1
$150,000 to $199,999	667 ±143	10.2% ±2.2	10.1% ±0.1	9.6% ±<0.1
$200,000 or more	481 ±117	7.3% ±1.8	13.8% ±0.1	13.4% ±0.1

Poverty by age

The poverty rate is the share of people whose family income is below the federal threshold for their family’s size, of everyone for whom the Bureau determines it (B17020).

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Poverty rate in Mercer County by age, ACS 2020–2024
Age	Below poverty	Rate	Illinois	United States
All ages	1,366 ±273	8.9% ±1.8	11.8% ±0.1	12.5% ±0.1
Under 18	390 ±115	12.2% ±3.5	15.1% ±0.2	16.1% ±0.1
18 to 59	642 ±171	8.5% ±2.2	11.0% ±0.1	11.6% ±0.1
60 and over	334 ±90	7.4% ±2.0	10.6% ±0.1	11.0% ±<0.1

Housing, 2020–2024

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Housing in Mercer County, ACS 2020–2024
Measure	Mercer County	Illinois	United States
Housing units	7,285 ±30	5,457,452 ±471	143,775,355 ±10,234
Occupied	90.1% ±2.4	92.3% ±0.1	89.9% ±0.1
Vacant	9.9% ±2.4	7.7% ±0.1	10.1% ±0.1
Owner occupied	83.8% ±2.4	67.1% ±0.3	65.2% ±0.3
Renter occupied	16.2% ±2.6	32.9% ±0.2	34.8% ±0.1
Median home value	$146,700 ±$7,887	$263,300 ±$797	$332,700 ±$236
Median gross rent	$786 ±$55	$1,274 ±$5	$1,413 ±$2
Median year built	1962 ±3	1971 ±2	1980 ±1

Occupied and vacant are shares of all housing units; owner and renter occupied are shares of occupied units. Value and rent are medians in 2024 dollars.

Origin and place of birth, 2020–2024

Hispanic or Latino origin is not a race in the Census Bureau’s tables. Here the people of Hispanic origin, of any race, are one row, and everyone else is counted by race alone (B03002), so the rows add to the whole.

Hispanic origin and race

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People in Mercer County by Hispanic origin and race, ACS 2020–2024
Origin	People	Share	Illinois	United States
Hispanic or Latino	534 ±0	3.4% ±<0.1	18.8% ±<0.1	19.3% ±<0.1
White alone, not Hispanic	14,426 ±64	93.1% ±0.4	58.1% ±<0.1	57.4% ±<0.1
Black alone, not Hispanic	40 to 146	0.3% to 0.9%	13.3% ±<0.1	11.9% ±<0.1
Asian alone, not Hispanic	56 ±20	0.4% ±0.1	5.9% ±<0.1	5.9% ±<0.1
American Indian and Alaska Native alone, not Hispanic	2 to 26	< 0.1% to 0.2%	0.1% ±<0.1	0.5% ±<0.1
Native Hawaiian and Other Pacific Islander alone, not Hispanic	0 to 20	0% to 0.1%	< 0.1% ±<0.1	0.2% ±<0.1
Some other race alone, not Hispanic	0 to 10	0% to 0.1%	0.4% ±<0.1	0.6% ±<0.1
Two or more races, not Hispanic	368 ±89	2.4% ±0.6	3.4% ±0.1	4.3% ±<0.1

A range (the estimate less and plus its margin) where the Bureau's estimate is too uncertain to state as one number: a coefficient of variation over 30%.

Place of birth and citizenship

“Born a citizen outside the states” counts people born in Puerto Rico, the island areas, or abroad to American parents. Naturalized citizens and those who are not citizens together make up the people born abroad (B05002).

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People in Mercer County by place of birth and citizenship, ACS 2020–2024
Born	People	Share	Illinois	United States
Born in the state	10,790 ±339	69.6% ±2.2	66.5% ±0.1	57.3% ±<0.1
Born in another state	4,471 ±343	28.9% ±2.2	17.5% ±0.1	26.9% ±<0.1
Born a citizen outside the states	27 to 109	0.2% to 0.7%	1.3% ±<0.1	1.7% ±<0.1
Born abroad	166 ±50	1.1% ±0.3	14.7% ±0.1	14.1% ±<0.1
Naturalized citizens	112 ±39	0.7% ±0.3	7.7% ±0.1	7.4% ±<0.1
Not citizens	18 to 90	0.1% to 0.6%	7.0% ±0.1	6.8% ±<0.1

A range (the estimate less and plus its margin) where the Bureau's estimate is too uncertain to state as one number: a coefficient of variation over 30%.

Mercer County among the counties of Illinois

68th of 102 by population, July 2025. Every one is listed on the Illinois page.

Counties of Illinois near Mercer County in population, July 2025
County	July 2025	Change since 2020
Union County	16,656	−3.7%
Edgar County	16,323	−2.9%
Warren County	16,222	−3.7%
Wayne County	15,882	−1.6%
Carroll County	15,419	−1.7%
Mercer County	15,229	−2.6%
Richland County	15,219	−3.7%
De Witt County	15,118	−2.1%
Clark County	15,114	−2.2%
Moultrie County	14,371	−0.8%
Pike County	14,231	−2.8%

Elsewhere on the site

Sources

Census Bureau population estimates — counties and Puerto Rico municipios, with components of change — U.S. Census Bureau · U.S. Government work · retrieved September 25, 2026
American Community Survey 5-year estimates — table-based Summary File · U.S. Government work

Data retrieved September 25, 2026