Marion County, Illinois: Power, Data Centers and the Local Economy
Home to Centralia Township, Centralia and Salem Township
No data center or power plant project is on record in Marion County, but the national build-out still reaches it through its utility bill, its labor market and the projects next door. Electrical contractors employ 137, up 121.0% since 2019 against up 3.9% statewide, at an average $81,908 a year. Marion County is home to Centralia Township, most of Centralia (9,598 of its 11,863 residents), Salem Township and Salem. 102 MW of that came online in 2019 or later, mostly solar. Its power plants have 372 MW of capacity, 73% of it natural gas. Employers here counted 12,335 jobs in 2025, down 4.3% from 2019.
Cities and towns in Marion County
Marion County is home to Centralia Township, most of Centralia (9,598 of its 11,863 residents), Salem Township and Salem.
And 7 smaller places.
- Centralia also extends into Clinton County.
- Wamac also extends into Clinton County, Washington County.
Residents are 2025 Census estimates for the part of each city, town or township inside this county. Census publishes no annual estimate for unincorporated communities.
What changed in Marion County
1st = the most. Ranks cover counties with a value on record.
| Measure | Then | Now | Change | Rank in Illinois |
|---|---|---|---|---|
| Population (2020 → 2025) | 37,656 | 36,382 | ▼ 3.4% | 37th of 102 by size |
| Total jobs (2019 → 2025) | 12,883 | 12,335 | ▼ 4.3% | 73rd of 102 by growth |
| Average annual pay (2019 → 2025) | $38,641 | $51,566 | ▲ 33.4% | — |
| Electrical contractor jobs (2019 → 2025) | 62 | 137 | ▲ 121.0% | — |
| Unemployment rate (2019 → August 2026) | 4.4% | 4.2% | ▼ 0.2pts | — |
| Generating capacity added since 2019 | — | 102 MW | — | |
| Generating capacity retired since 2019 | — | 0 MW | — |
Ameren Illinois Company is the largest utility serving Marion County, one of 6 with territory here. Its residential customers paid an average 15.26¢/kWh in 2024. Unemployment was 4.2% in August 2026, against 4.4% in 2019. 36,382 people live here, down 3.4% since 2020.
Who powers Marion County
Net change in operating capacity since 2019: +102 MW. Colors follow the fuel legend above.
Utilities with service territory in Marion County
| Utility | Ownership | Service | Residential customers (systemwide) | Residential price, 2024 | Commercial share of sales |
|---|---|---|---|---|---|
| Ameren Illinois Company | Investor Owned | Bundled | 1,060,894 | 15.26¢ | 28% |
| Southwestern Electric Coop Inc - (IL) | Cooperative | Bundled | 24,822 | 13.68¢ | 17% |
| Tri-County Electric Coop, Inc (IL) | Cooperative | Bundled | 16,197 | 16.04¢ | 9% |
| Wayne-White Counties Elec Coop | Cooperative | Bundled | 11,957 | 16.58¢ | 21% |
| Clay Electric Coop Inc - (IL) | — | — | — | — | — |
| Clinton County Elec Coop, Inc | — | — | — | — | — |
Customer counts, prices and sales shares cover each utility's whole system in the state, not only this county. Commercial sales include data centers.
Operating power plants 4
| Technology | Capacity | Share |
|---|---|---|
| Natural gas | 270 MW | 73% |
| Solar | 102 MW | 27% |
| Largest plants | Owner | Technology | MW | Since |
|---|---|---|---|---|
| Kinmundy | Union Electric Co - (MO) | Natural gas | 270 MW | 2001 |
| Crooked Creek PV I | Crooked Creek PV I, LLC | Solar | 99 MW | 2026 |
| Marion Solar 4b LLC | Pivot Energy | Solar | 2 MW | 2024 |
| Marion Solar 2 | Pivot Energy | Solar | 1 MW | 2025 |
The Marion County labor market
| Industry (2025) | Jobs | Average pay | Concentration vs U.S. |
|---|---|---|---|
| All industries | 12,335 | $51,566 | 1.00 |
| Electrical contractors | 137 | $81,908 | 1.54 |
Concentration is the BLS location quotient: 1.0 means the industry holds the same share of local jobs as it does nationally. Industry rows count private employers; cells BLS suppresses are left out.
Data centers and local rules in Marion County
No data center, local measure or delayed project is on record in Marion County. Illinois has 28 local measures on record statewide.
Marion County and its neighbors
Of the 6 counties that border Marion County, Clay County carries the most build-out activity: data centers, planned generation and operating plants combined.
| County | Population | Jobs since 2019 | Operating MW | Planned MW | Data centers | Local measures |
|---|---|---|---|---|---|---|
| Marion County | 36,382 | ▼ 4.3% | 372 MW | — | — | — |
| Clay County | 12,793 | ▼ 9.9% | 726 MW | 127 MW | — | — |
| Clinton County | 37,128 | ▲ 2.6% | 47 MW | 53 MW | — | — |
| Fayette County | 20,790 | ▼ 9.7% | 101 MW | 119 MW | — | — |
| Jefferson County | 36,147 | ▼ 2.4% | 2 MW | 155 MW | — | — |
| Washington County | 13,564 | ▼ 6.6% | 5 MW | — | — | — |
| Wayne County | 15,882 | ▲ 2.4% | — | — | — | — |
More of Illinois
Marion County, answered from the record
Who provides electricity in Marion County, Illinois?
6 utilities have service territory in Marion County in the EIA-861 2024 report: Ameren Illinois Company, Southwestern Electric Coop Inc - (IL), Tri-County Electric Coop, Inc (IL), Wayne-White Counties Elec Coop. The largest, Ameren Illinois Company, charged residential customers 15.26¢/kWh on average in 2024.
What county is Centralia Township, IL in?
Centralia Township is in Marion County, Illinois. About 13,816 people live there (2025 Census estimate).
What power plants are in Marion County?
4 operating plants with 372 MW of capacity. The largest is Kinmundy (270 MW, natural gas).
Are there data centers in Marion County?
The SAVRN Data Center Map has no data center in Marion County.
Is Marion County adding jobs?
Employers counted 12,335 jobs in 2025 against 12,883 in 2019 (-4.3%, BLS QCEW).
Does Marion County have a data center moratorium?
No county-level measure is on record for Marion County. Illinois has 28 local measures statewide, listed on the state page.