Decatur, Illinois demographics

Decatur, IL demographics: median age 39.2; 21.6% of adults 25+ hold a bachelor’s degree. Age, race, households, languages and education, ACS 2020–2024 with margins of error.

ACS 2020–2024 · Decatur city, Illinois · Incorporated city · GEOID 1718823. The survey estimates a population of 69,815 for its five-year window. This is separate from the annual July 2025 population estimate on the city overview.

Median age in Decatur is 39.2 years, with a 90% margin of error of 0.9 years. There are 30,920 households (±545). 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	39.2 ±0.9	39.0 ±0.1	38.9 ±0.1

Age groups · B01001 · ACS 2020–2024 Total population: 69,815
Category	Count ± MOE	Share ± MOE (pp)	Illinois	U.S.
Under 18	14,686 ±653	21.0% ±0.9 pp	21.8%	22.0%
18–34	16,479 ±656	23.6% ±0.9 pp	22.7%	22.8%
35–64	23,810 ±841	34.1% ±1.2 pp	38.5%	38.0%
65 and older	14,840 ±752	21.3% ±1.1 pp	17.0%	17.2%

Sex categories as published by ACS · B01001 · ACS 2020–2024 Total population: 69,815
Category	Count ± MOE	Share ± MOE (pp)	Illinois	U.S.
Male	33,021 ±413	47.3% ±0.5 pp	49.4%	49.5%
Female	36,794 ±467	52.7% ±0.5 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: 69,815
Category	Count ± MOE	Share ± MOE (pp)	Illinois	U.S.
White alone	46,152 ±658	66.1% ±0.8 pp	61.0%	61.0%
Black or African American alone	16,255 ±778	23.3% ±1.1 pp	13.6%	12.2%
American Indian and Alaska Native alone	69 ±60 · low precision	0.1% ±0.1 pp · low precision	0.6%	0.9%
Asian alone	1,029 ±225	1.5% ±0.3 pp	6.0%	6.0%
Native Hawaiian and Other Pacific Islander alone	43 ±62 · low precision	0.1% ±0.1 pp · low precision	0.0%	0.2%
Some other race alone	972 ±287	1.4% ±0.4 pp	7.9%	7.1%
Two or more races	5,295 ±849	7.6% ±1.2 pp	10.9%	12.6%

Hispanic or Latino origin · B03003 · ACS 2020–2024 Total population: 69,815
Category	Count ± MOE	Share ± MOE (pp)	Illinois	U.S.
Not Hispanic or Latino	67,504 ±577	96.7% ±0.3 pp	81.2%	80.7%
Hispanic or Latino	2,311 ±193	3.3% ±0.3 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: 30,920
Category	Count ± MOE	Share ± MOE (pp)	Illinois	U.S.
Married-couple family	9,952 ±557	32.2% ±1.7 pp	45.3%	46.9%
Other family: male householder, no spouse present	1,505 ±259	4.9% ±0.8 pp	4.9%	5.1%
Other family: female householder, no spouse present	3,818 ±430	12.3% ±1.4 pp	11.9%	12.2%
Nonfamily: householder living alone	13,547 ±781	43.8% ±2.4 pp	31.2%	28.7%
Nonfamily: householder not living alone	2,098 ±299	6.8% ±1.0 pp	6.7%	7.0%

Households with children · B11005 · ACS 2020–2024 Households: 30,920
Category	Count ± MOE	Share ± MOE (pp)	Illinois	U.S.
Households with people under 18	6,262 ±479	20.3% ±1.5 pp	28.6%	29.5%
Households without people under 18	24,658 ±666	79.7% ±1.6 pp	71.4%	70.5%

Household size · B11016 · ACS 2020–2024 Households: 30,920
Category	Count ± MOE	Share ± MOE (pp)	Illinois	U.S.
One-person nonfamily households	13,547 ±781	43.8% ±2.4 pp	31.2%	28.7%
Two-person households	10,304 ±610	33.3% ±1.9 pp	32.3%	33.8%
Three-person households	3,469 ±456	11.2% ±1.5 pp	14.7%	15.3%
Four-person households	1,760 ±315	5.7% ±1.0 pp	12.6%	12.6%
Five-person households	1,016 ±250	3.3% ±0.8 pp	5.8%	5.9%
Six-person households	637 ±184	2.1% ±0.6 pp	2.1%	2.2%
Seven or more people	187 ±102 · low precision	0.6% ±0.3 pp · low precision	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: 69,815
Category	Count ± MOE	Share ± MOE (pp)	Illinois	U.S.
Native	67,647 ±630	96.9% ±0.5 pp	85.3%	85.9%
Foreign born	2,168 ±383	3.1% ±0.5 pp	14.7%	14.1%

Language spoken at home · C16001 · ACS 2020–2024 Population age 5 and older: 65,520
Category	Count ± MOE	Share ± MOE (pp)	Illinois	U.S.
English only	62,518 ±580	95.4% ±0.5 pp	76.0%	77.7%
Spanish	1,322 ±232	2.0% ±0.4 pp	14.0%	13.6%
French, Haitian, or Cajun	41 ±33 · low precision	0.1% ±0.1 pp · low precision	0.3%	0.7%
German or other West Germanic	212 ±191 · low precision	0.3% ±0.3 pp · low precision	0.3%	0.5%
Russian, Polish, or other Slavic	223 ±241 · low precision	0.3% ±0.4 pp · low precision	2.5%	0.7%
Other Indo-European	506 ±198	0.8% ±0.3 pp	2.6%	2.0%
Korean	160 ±124 · low precision	0.2% ±0.2 pp · low precision	0.3%	0.3%
Chinese, including Mandarin and Cantonese	99 ±63 · low precision	0.2% ±0.1 pp · low precision	0.9%	1.1%
Vietnamese	0 ±30 · low precision	0.0% ±0.0 pp · low precision	0.2%	0.5%
Tagalog, including Filipino	151 ±103 · low precision	0.2% ±0.2 pp · low precision	0.7%	0.6%
Other Asian and Pacific Island	94 ±84 · low precision	0.1% ±0.1 pp · low precision	1.0%	1.1%
Arabic	56 ±48 · low precision	0.1% ±0.1 pp · low precision	0.6%	0.5%
Other and unspecified	138 ±176 · low precision	0.2% ±0.3 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: 48,026
Category	Count ± MOE	Share ± MOE (pp)	Illinois	U.S.
Less than high school graduate	3,996 ±509	8.3% ±1.1 pp	9.5%	10.4%
High school graduate or equivalency	19,338 ±1,016	40.3% ±2.1 pp	25.1%	26.0%
Some college, no degree	10,485 ±749	21.8% ±1.5 pp	19.2%	19.1%
Associate’s degree	3,817 ±385	7.9% ±0.8 pp	8.3%	8.8%
Bachelor’s degree	6,681 ±708	13.9% ±1.5 pp	22.6%	21.6%
Graduate or professional degree	3,709 ±554	7.7% ±1.1 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: 68,969
Category	Count ± MOE	Share ± MOE (pp)	Illinois	U.S.
Same house	58,663 ±1,058	85.1% ±1.3 pp	88.9%	87.7%
Moved within same county	7,025 ±853	10.2% ±1.2 pp	6.4%	6.3%
Moved from a different county in the same state	2,091 ±385	3.0% ±0.6 pp	2.4%	3.1%
Moved from a different state	956 ±302	1.4% ±0.4 pp	1.6%	2.3%
Moved from abroad	234 ±155 · low precision	0.3% ±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

4.7% of Decatur residents (±0.7 percentage points) had no health insurance coverage when surveyed, compared with 6.9% in Illinois and 8.4% nationally. 88.3% 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	Decatur	Illinois	U.S.	Compared with Illinois
People without health insurance Civilian noninstitutionalized population	4.7% ±0.7 pp	6.9%	8.4%	Lower
Households with a broadband subscription Households	88.3% ±1.4 pp	90.8%	91.0%	Lower
Veterans Civilian population age 18 and older	6.7% ±0.6 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 Decatur . 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 Decatur housing and cost context or return to the city profile.