Alton, Illinois demographics

Alton, IL demographics: median age 38.0; 21.5% of adults 25+ hold a bachelor’s degree. Age, race, households, languages and education, ACS 2020–2024 with margins of error.

ACS 2020–2024 · Alton city, Illinois · Incorporated city · GEOID 1701114. The survey estimates a population of 25,279 for its five-year window. This is separate from the annual July 2025 population estimate on the city overview.

Median age in Alton is 38.0 years, with a 90% margin of error of 1.3 years. There are 10,714 households (±390). Age and household distributions show how these totals are composed; they do not establish which neighborhood suits a particular person.

Every count and share is an estimate. “±” is a 90% margin of error (MOE); pp means percentage points. Derived shares use the category count divided by the named universe. Aggregated category MOEs and percentage MOEs are approximate. A margin larger than half its estimate is flagged as low precision. Blank source uncertainty is shown as unavailable, never zero.

Age distribution and sex

City, state and U.S. estimates · ACS 2020–2024
Measure / survey universe	City estimate ± MOE	State estimate ± MOE	U.S. estimate ± MOE
Median age Total population · years	38.0 ±1.3	39.0 ±0.1	38.9 ±0.1

Age groups · B01001 · ACS 2020–2024 Total population: 25,279
Category	Count ± MOE	Share ± MOE (pp)	Illinois	U.S.
Under 18	5,839 ±515	23.1% ±2.0 pp	21.8%	22.0%
18–34	5,573 ±578	22.0% ±2.3 pp	22.7%	22.8%
35–64	9,513 ±616	37.6% ±2.4 pp	38.5%	38.0%
65 and older	4,354 ±391	17.2% ±1.5 pp	17.0%	17.2%

Sex categories as published by ACS · B01001 · ACS 2020–2024 Total population: 25,279
Category	Count ± MOE	Share ± MOE (pp)	Illinois	U.S.
Male	11,979 ±540	47.4% ±2.1 pp	49.4%	49.5%
Female	13,300 ±540	52.6% ±2.1 pp	50.6%	50.5%

The age groups are mutually exclusive and cover the entire population. The sex categories follow this ACS table’s published classification; they are not a survey of gender identity.

Race and Hispanic origin

Race · B02001 · ACS 2020–2024 Total population: 25,279
Category	Count ± MOE	Share ± MOE (pp)	Illinois	U.S.
White alone	17,678 ±867	69.9% ±3.4 pp	61.0%	61.0%
Black or African American alone	4,920 ±732	19.5% ±2.9 pp	13.6%	12.2%
American Indian and Alaska Native alone	107 ±83 · low precision	0.4% ±0.3 pp · low precision	0.6%	0.9%
Asian alone	364 ±309 · low precision	1.4% ±1.2 pp · low precision	6.0%	6.0%
Native Hawaiian and Other Pacific Islander alone	0 ±24 · low precision	0.0% ±0.1 pp · low precision	0.0%	0.2%
Some other race alone	312 ±128	1.2% ±0.5 pp	7.9%	7.1%
Two or more races	1,898 ±401	7.5% ±1.6 pp	10.9%	12.6%

Hispanic or Latino origin · B03003 · ACS 2020–2024 Total population: 25,279
Category	Count ± MOE	Share ± MOE (pp)	Illinois	U.S.
Not Hispanic or Latino	24,519 ±176	97.0% ±0.7 pp	81.2%	80.7%
Hispanic or Latino	760 ±174	3.0% ±0.7 pp	18.8%	19.3%

Hispanic origin and race are separate questions. People of Hispanic or Latino origin may be of any race and appear in both tables. Do not add the Hispanic share to race shares. Race alone and two-or-more-race groups are the mutually exclusive categories of the race table.

Household types, children and living alone

Household types · B11001 · ACS 2020–2024 Households: 10,714
Category	Count ± MOE	Share ± MOE (pp)	Illinois	U.S.
Married-couple family	3,188 ±346	29.8% ±3.0 pp	45.3%	46.9%
Other family: male householder, no spouse present	544 ±168	5.1% ±1.6 pp	4.9%	5.1%
Other family: female householder, no spouse present	2,022 ±300	18.9% ±2.7 pp	11.9%	12.2%
Nonfamily: householder living alone	4,090 ±396	38.2% ±3.4 pp	31.2%	28.7%
Nonfamily: householder not living alone	870 ±206	8.1% ±1.9 pp	6.7%	7.0%

Households with children · B11005 · ACS 2020–2024 Households: 10,714
Category	Count ± MOE	Share ± MOE (pp)	Illinois	U.S.
Households with people under 18	2,998 ±217	28.0% ±1.8 pp	28.6%	29.5%
Households without people under 18	7,716 ±478	72.0% ±3.6 pp	71.4%	70.5%

Household size · B11016 · ACS 2020–2024 Households: 10,714
Category	Count ± MOE	Share ± MOE (pp)	Illinois	U.S.
One-person nonfamily households	4,090 ±396	38.2% ±3.4 pp	31.2%	28.7%
Two-person households	3,063 ±367	28.6% ±3.3 pp	32.3%	33.8%
Three-person households	1,632 ±251	15.2% ±2.3 pp	14.7%	15.3%
Four-person households	1,057 ±241	9.9% ±2.2 pp	12.6%	12.6%
Five-person households	502 ±170	4.7% ±1.6 pp	5.8%	5.9%
Six-person households	192 ±115 · low precision	1.8% ±1.1 pp · low precision	2.1%	2.2%
Seven or more people	178 ±77	1.7% ±0.7 pp	1.3%	1.4%

A family household contains related people under the Census definition. A nonfamily household can contain one person or unrelated people sharing a home. Households with children can also appear in the household-type and size tables, so those tables must not be added together. Household estimates exclude people living in group quarters from the household universe.

Nativity and languages spoken at home

Nativity · B05002 · ACS 2020–2024 Total population: 25,279
Category	Count ± MOE	Share ± MOE (pp)	Illinois	U.S.
Native	24,618 ±288	97.4% ±1.1 pp	85.3%	85.9%
Foreign born	661 ±283	2.6% ±1.1 pp	14.7%	14.1%

Language spoken at home · C16001 · ACS 2020–2024 Population age 5 and older: 24,012
Category	Count ± MOE	Share ± MOE (pp)	Illinois	U.S.
English only	23,076 ±463	96.1% ±1.7 pp	76.0%	77.7%
Spanish	257 ±121	1.1% ±0.5 pp	14.0%	13.6%
French, Haitian, or Cajun	44 ±51 · low precision	0.2% ±0.2 pp · low precision	0.3%	0.7%
German or other West Germanic	29 ±25 · low precision	0.1% ±0.1 pp · low precision	0.3%	0.5%
Russian, Polish, or other Slavic	92 ±71 · low precision	0.4% ±0.3 pp · low precision	2.5%	0.7%
Other Indo-European	249 ±235 · low precision	1.0% ±1.0 pp · low precision	2.6%	2.0%
Korean	18 ±19 · low precision	0.1% ±0.1 pp · low precision	0.3%	0.3%
Chinese, including Mandarin and Cantonese	0 ±24 · low precision	0.0% ±0.1 pp · low precision	0.9%	1.1%
Vietnamese	17 ±45 · low precision	0.1% ±0.2 pp · low precision	0.2%	0.5%
Tagalog, including Filipino	37 ±43 · low precision	0.2% ±0.2 pp · low precision	0.7%	0.6%
Other Asian and Pacific Island	15 ±23 · low precision	0.1% ±0.1 pp · low precision	1.0%	1.1%
Arabic	31 ±42 · low precision	0.1% ±0.2 pp · low precision	0.6%	0.5%
Other and unspecified	147 ±101 · low precision	0.6% ±0.4 pp · low precision	0.6%	0.8%

Foreign born means not a U.S. citizen at birth; it includes naturalized citizens. Language categories describe speech at home among people age five and older. A language other than English at home does not establish that someone cannot speak English. This city page uses the published C16001 summary categories because the more detailed B16001 table does not provide these city records in this release.

Educational attainment

Highest completed education · B15003 · ACS 2020–2024 Population age 25 and older: 17,651
Category	Count ± MOE	Share ± MOE (pp)	Illinois	U.S.
Less than high school graduate	1,528 ±337	8.7% ±1.9 pp	9.5%	10.4%
High school graduate or equivalency	5,662 ±495	32.1% ±2.6 pp	25.1%	26.0%
Some college, no degree	4,674 ±513	26.5% ±2.8 pp	19.2%	19.1%
Associate’s degree	1,990 ±312	11.3% ±1.7 pp	8.3%	8.8%
Bachelor’s degree	2,344 ±329	13.3% ±1.8 pp	22.6%	21.6%
Graduate or professional degree	1,453 ±275	8.2% ±1.5 pp	15.3%	14.1%

The denominator excludes residents under 25. Each person is counted in the highest attainment category they completed. This table does not measure the quality of local schools or the education level of every current student.

Residence one year earlier

Geographic mobility · B07003 · ACS 2020–2024 Population age 1 and older: 25,109
Category	Count ± MOE	Share ± MOE (pp)	Illinois	U.S.
Same house	21,504 ±675	85.6% ±2.7 pp	88.9%	87.7%
Moved within same county	2,508 ±635	10.0% ±2.5 pp	6.4%	6.3%
Moved from a different county in the same state	465 ±174	1.9% ±0.7 pp	2.4%	3.1%
Moved from a different state	605 ±258	2.4% ±1.0 pp	1.6%	2.3%
Moved from abroad	27 ±39 · low precision	0.1% ±0.2 pp · low precision	0.6%	0.6%

These are respondents’ residence patterns one year before their survey response, pooled across the five-year window. They are not a net migration count for 2025. A person can move to a different house within the same city or county; moves within the same county should not automatically be interpreted as new arrivals to the city.

Health insurance, internet access and veterans

6.8% of Alton residents (±1.2 percentage points) had no health insurance coverage when surveyed, compared with 6.9% in Illinois and 8.4% nationally. 90.5% of households subscribe to broadband of any type, including cellular data plans. A subscription is not the same as available service: the FCC National Broadband Map shows providers at a specific address.

City, state and U.S. shares · ACS 2020–2024
Measure	Alton	Illinois	U.S.	Compared with Illinois
People without health insurance Civilian noninstitutionalized population	6.8% ±1.2 pp	6.9%	8.4%	Not statistically different
Households with a broadband subscription Households	90.5% ±1.3 pp	90.8%	91.0%	Not statistically different
Veterans Civilian population age 18 and older	8.3% ±1.2 pp	4.8%	6.2%	Higher

Reading and reusing the estimates

The Census table links above lead to the original detailed tables. Counts, source universes and uncertainty are retained in the source observation download for Alton . Compare these figures with the same survey window; do not compare one city’s five-year estimate with another city’s annual estimate as though they measured the same period. For methods, see uncertainty and denominator calculations.

Read Alton housing and cost context or return to the city profile.