St. Louis County, Missouri: Power, Data Centers and the Local Economy
Home to Florissant, Chesterfield and Wildwood
The data center boom is not abstract in St. Louis County: it is on the ground here. The SAVRN Data Center Map lists 7 data centers in St. Louis County, 8% of Missouri's total. St. Louis County is home to Florissant, Chesterfield, Wildwood and University City. 1,041 MW has retired here since 2019, including Meramec (coal, 648 MW, 2022). 648 MW of new generation is planned here across 3 units, led by Union Electric Co - (MO) (natural gas), the largest pipeline among Missouri's counties. Construction employs 32,990, up 11.9% since 2019.
Cities and towns in St. Louis County
St. Louis County is home to Florissant, Chesterfield, Wildwood and University City.
And 16 smaller places.
Unincorporated communities (governed by the county): Affton, Castle Point, Concord, Glasgow Village, Lemay, Mehlville, Oakville, Old Jamestown, Sappington, Spanish Lake, St. George.
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 St. Louis County
1st = the most. Ranks cover counties with a value on record.
| Measure | Then | Now | Change | Rank in Missouri |
|---|---|---|---|---|
| Population (2020 → 2025) | 1,003,365 | 990,911 | ▼ 1.2% | 1st of 115 by size |
| Total jobs (2019 → 2025) | 610,438 | 589,803 | ▼ 3.4% | 93rd of 115 by growth |
| Average annual pay (2019 → 2025) | $61,534 | $78,741 | ▲ 28.0% | — |
| Construction jobs (2019 → 2025) | 29,488 | 32,990 | ▲ 11.9% | 45th of 71 by growth |
| Electrical contractor jobs (2019 → 2025) | 4,131 | 4,381 | ▲ 6.1% | — |
| Power line construction jobs (2019 → 2025) | 810 | 1,223 | ▲ 51.0% | — |
| Data processing and hosting jobs (2019 → 2025) | 3,234 | 3,661 | ▲ 13.2% | — |
| Unemployment rate (2019 → August 2026) | 3.1% | 4.2% | ▲ 1.1pts | — |
| Generating capacity added since 2019 | — | 0 MW | — | |
| Generating capacity retired since 2019 | — | 1,041 MW | — | |
| Planned generation (Aug 2026) | — | 648 MW | 1895% of today's fleet | 1st of 14 by size |
Unemployment was 4.2% in August 2026, against 3.1% in 2019. Electrical contractors employ 4,381, up 6.1% since 2019 against up 21.5% statewide, at an average $95,158 a year. Employers here counted 589,803 jobs in 2025, down 3.4% from 2019. Its power plants have 34 MW of capacity, 100% of it natural gas. Union Electric Co - (MO) is the largest utility serving St. Louis County. Its residential customers paid an average 12.56¢/kWh in 2024. 990,911 people live here, down 1.2% since 2020, 1st of 115 Missouri counties by population.
Who powers St. Louis County
Net change in operating capacity since 2019: −1,041 MW. Colors follow the fuel legend above.
Utilities with service territory in St. Louis County
| Utility | Ownership | Service | Residential customers (systemwide) | Residential price, 2024 | Commercial share of sales |
|---|---|---|---|---|---|
| Union Electric Co - (MO) | Investor Owned | Bundled | 1,095,619 | 12.56¢ | 44% |
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 1
| Technology | Capacity | Share |
|---|---|---|
| Natural gas | 34 MW | 100% |
| Largest plants | Owner | Technology | MW | Since |
|---|---|---|---|---|
| Trigen St. Louis | Centerstream STL, LLC | Natural gas | 34 MW | 1999 |
Planned generation 3
| Plant | Technology | MW | Status | Year | Owner |
|---|---|---|---|---|---|
| Castle Bluff Energy Center | Natural Gas Fired Combustion Turbine | 216 MW | Planned, approvals not started | 2027 | Union Electric Co - (MO) |
| Castle Bluff Energy Center | Natural Gas Fired Combustion Turbine | 216 MW | Planned, approvals not started | 2027 | Union Electric Co - (MO) |
| Castle Bluff Energy Center | Natural Gas Fired Combustion Turbine | 216 MW | Planned, approvals not started | 2027 | Union Electric Co - (MO) |
Retired since 2019
| Plant | Technology | MW | Year |
|---|---|---|---|
| Meramec | Coal | 648 MW | 2022 |
| Meramec | Natural gas | 331 MW | 2022 |
| Meramec | Petroleum | 62 MW | 2022 |
The St. Louis County labor market
| Industry (2025) | Jobs | Average pay | Concentration vs U.S. |
|---|---|---|---|
| All industries | 589,803 | $78,741 | 1.00 |
| Construction | 32,990 | $96,451 | 1.06 |
| Electrical contractors | 4,381 | $95,158 | 1.03 |
| Power and communication line construction | 1,223 | $99,019 | 1.28 |
| Data processing and hosting | 3,661 | $169,987 | 2.00 |
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 St. Louis County
7 data centers in St. Louis County are on the SAVRN Data Center Map: see them by city and operator.
St. Louis County and its neighbors
Of the 7 counties that border St. Louis County, St. Louis (city) 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 |
|---|---|---|---|---|---|---|
| St. Louis County | 990,911 | ▼ 3.4% | 34 MW | 648 MW | 7 | — |
| Franklin County | 108,090 | ▲ 0.6% | 2,389 MW | — | — | — |
| Jefferson County | 233,132 | ▲ 3.4% | — | — | — | — |
| Madison County IL | 263,110 | ▲ 5.9% | 701 MW | 8 MW | — | — |
| Monroe County IL | 34,840 | ▲ 1.4% | 38 MW | — | — | — |
| St. Charles County | 426,499 | ▲ 7.1% | 1,104 MW | — | 1 | 1 |
| St. Clair County IL | 250,708 | ▼ 3.2% | 1,821 MW | 155 MW | — | — |
| St. Louis (city) | 278,144 | ▼ 4.0% | — | — | 14 | — |
More of Missouri
St. Louis County, answered from the record
Who provides electricity in St. Louis County, Missouri?
1 utility has service territory in St. Louis County in the EIA-861 2024 report: Union Electric Co - (MO). The largest, Union Electric Co - (MO), charged residential customers 12.56¢/kWh on average in 2024.
What county is Florissant, MO in?
Florissant is in St. Louis County, Missouri. About 51,124 people live there (2025 Census estimate).
What county is Chesterfield, MO in?
Chesterfield is in St. Louis County, Missouri. About 49,309 people live there (2025 Census estimate).
What county is Wildwood, MO in?
Wildwood is in St. Louis County, Missouri. About 34,955 people live there (2025 Census estimate).
What power plants are in St. Louis County?
1 operating plant with 34 MW of capacity. The largest is Trigen St. Louis (34 MW, natural gas).
How much new power is planned in St. Louis County?
648 MW across 3 units in the August 2026 EIA-860M inventory, 0 MW of it under construction or built. The largest owner is Union Electric Co - (MO).
Are there data centers in St. Louis County?
Yes. The SAVRN Data Center Map lists 7 data centers in St. Louis County.
Is St. Louis County adding jobs?
Employers counted 589,803 jobs in 2025 against 610,438 in 2019 (-3.4%, BLS QCEW). Construction went from 29,488 to 32,990.
Does St. Louis County have a data center moratorium?
No county-level measure is on record for St. Louis County. Missouri has 21 local measures statewide, listed on the state page.