Centralia, IL Micro Area
The Centralia, IL micro area is one county in Illinois: Marion County. About 36,382 people lived there on July 1, 2025 (Census estimate), 3.6% fewer than in April 2020.
- Population, July 2025
- 36,382 3.6% fewer than in April 2020
- Type
- Micropolitan statistical area
- County
- Marion County
- Land area
- 573 sq mi (1,483 km²)
- Time zone
- Central TimeUTC-06:00 in January; UTC-05:00 in July
- State
- Illinois
- Combined statistical area
- St. Louis-St. Charles-Farmington, MO-IL
- CBSA code
- 16460
The county in the Centralia, IL micro area
| County | Role | Population, July 2025 |
|---|---|---|
| Marion County | Central | 36,382 |
A central county holds the area’s core, an urban area of 10,000 to 49,999 people. This area has no outlying counties: no neighboring county sends enough commuters to join it. A county belongs to one metro or micro area at most, and it counts whole, countryside included.
Principal city
- Centralia11,856 people
OMB names the area after its largest principal cities. A principal city is the area’s largest city, plus any other city that is very large or a big job center, and smaller ones with at least as many jobs as working residents (2020 Census and commuting figures). People counts are American Community Survey 2020–2024 5-year estimates.
Part of the St. Louis-St. Charles-Farmington, MO-IL combined statistical area
OMB joins neighboring metro and micro areas into a combined statistical area when enough people commute between them. The other 2 areas in this one, largest first:
- St. Louis, MO-IL Metro Area2,814,421 people
- Farmington, MO Micro Area67,809 people
Bordering metro and micro areas, nearest first
Areas with a county on this area’s edge. Distances are straight lines between the areas’ largest cities.
- Mount Vernon, IL Micro Area18 mi southeast
- St. Louis, MO-IL Metro Area61 mi west
Before using this answer on a form
A metro or micro area is a statistical area that OMB draws for federal statistics. It is not a city, a local government or a mailing address, and it is not a measure of urban and rural: whole counties count, rural parts included. Programs that use metro areas, such as housing income limits or wage rates, can use their own version of these lists; check the program’s own list for an address.
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