Illinois · Census place 1718823
Decatur, Illinois
Decatur is a city in Macon County, Illinois with an estimated 68,763 residents on July 1, 2024. It is the 17th largest of 651 incorporated places of 1,000+ people in the state.
- Population 2024
- 68,763
- #17 of 651 in Illinois
- Change since 2020
- -3.1%
- -2,215 people
- Land area
- 43.7 sq mi
- + 4.70 sq mi water
- Density
- 1,574 / sq mi
- State median 2,177
Measure from here
Tools and pages that start from Decatur
Decatur population, 2020 to 2024
Decatur lost 2,215 residents from July 2020 to July 2024, a change of -3.1%. In the latest year it moved by -61. Among 330 Illinois places of 5,000 or more, that growth ranks 314th; the median place changed by -0.9%. The median place of 5,000+ in Illinois has 14,760 people, so Decatur is 4.7 times that size.
Decatur covers 43.70 square miles of land and 4.70 of water, for 1,574 people per square mile of land. The median Illinois place of 5,000+ has 2,177, so Decatur is less dense than the typical town.
What county Decatur is in
All of Decatur's residents live in Macon County, which had 100,737 residents in 2024. Decatur holds 68.3% of the county's population. The shaded shape is on the map above; dots mark the eight nearest places.
ZIP codes in Decatur
4 ZIP Code Tabulation Areas (ZCTAs) overlap Decatur by at least 10% of the ZCTA's or the city's land: 62521, 62522, 62523, 62526. ZCTAs are Census approximations of USPS ZIP code delivery areas. The list comes from the 2020 ZCTA to place relationship file, so a city that annexed land after 2020 may reach into ZIP codes not listed here.
Where Decatur is
The Census internal point of Decatur is at 39.856000, -88.933700. Springfield, the capital, is 38.4 miles W in a straight line. The nearest larger place is Springfield, IL (112,949 people), 38.0 miles away.
Internal point
- Decimal
- 39.856000, -88.933700
- DMS
- 39°51'21.60"N 88°56'1.32"W
- UTM
- 16N 334588.1E 4413564.0N
- Geohash
- dp0f8r86n
- Plus code
- 86FHV348+CG
Daylight in Decatur
At 39.86° N, Decatur gets about 15 h 00 min of daylight around the June solstice and 9 h 21 min around the December solstice, a swing of 5 h 40 min. Figures are sunrise to sunset from the SunCalc model for June 21 and December 21, 2026.
Places near Decatur
The eight nearest incorporated places of 1,000+ in Illinois, measured between internal points. The closest is Forsyth, 5.1 miles away, with 3,656 people.
Questions people ask
What is the population of Decatur, IL?
68,763 on July 1, 2024, in the Census Vintage 2024 estimates. That is down 2,215 (3.1%) from 70,978 in July 2020.
What county is Decatur in?
Macon County. All of its residents live in that county.
What ZIP codes cover Decatur?
4 ZIP Code Tabulation Areas overlap it by at least 10% of either area: 62521, 62522, 62523, 62526.
How far is Decatur from Springfield?
38.4 miles (61.7 km) in a straight line, heading W from Decatur.
What is the nearest larger city to Decatur?
Springfield, IL, with 112,949 residents, 38.0 miles away between internal points.
Sources and data as of
Data as of: Census Vintage 2024 subcounty estimates (July 1, 2024), 2024 Gazetteer places, 2020 ZCTA to place relationship file.
- 01Census Vintage 2024 subcounty population estimates
- 02Census 2024 Gazetteer, places
- 03Census 2020 ZCTA to place relationship file
- 04Census 2024 cartographic boundary file, counties (1:5,000,000)
How every number is computed: methodology. Spotted a wrong figure? Report an error.