Jefferson County, Missouri: Power, Data Centers and the Local Economy
Home to Arnold, Festus and De Soto
Jefferson County is living through the turnover of the U.S. power fleet. Jefferson County is home to Arnold, Festus, De Soto and Pevely. 1,242 MW has retired here since 2019, including Rush Island (coal, 1,242 MW, 2024). Construction employs 4,385, up 12.3% since 2019, and construction is 1.7 times as concentrated here as in the U.S. economy. Next door, St. Louis County has 7 data centers and 648 MW of planned generation. Electrical contractors employ 391, up 3.4% since 2019 against up 21.5% statewide, at an average $68,600 a year.
Cities and towns in Jefferson County
Jefferson County is home to Arnold, Festus, De Soto and Pevely.
- Eureka also extends into St. Louis County.
Unincorporated communities (governed by the county): Barnhart, Briarwood Estates, Cedar Hill, High Ridge, Horine, Imperial, LaBarque Creek, Murphy, Raintree Plantation, Summer Set.
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 Jefferson County
1st = the most. Ranks cover counties with a value on record.
| Measure | Then | Now | Change | Rank in Missouri |
|---|---|---|---|---|
| Population (2020 → 2025) | 226,944 | 233,132 | ▲ 2.7% | 7th of 115 by size |
| Total jobs (2019 → 2025) | 47,947 | 49,584 | ▲ 3.4% | 50th of 115 by growth |
| Average annual pay (2019 → 2025) | $39,096 | $52,302 | ▲ 33.8% | — |
| Construction jobs (2019 → 2025) | 3,906 | 4,385 | ▲ 12.3% | 43rd of 71 by growth |
| Electrical contractor jobs (2019 → 2025) | 378 | 391 | ▲ 3.4% | — |
| Power line construction jobs (2019 → 2025) | 232 | 204 | ▼ 12.1% | — |
| Unemployment rate (2019 → August 2026) | 3.0% | 3.6% | ▲ 0.6pts | — |
| Generating capacity added since 2019 | — | 0 MW | — | |
| Generating capacity retired since 2019 | — | 1,242 MW | — |
Employers here counted 49,584 jobs in 2025, up 3.4% from 2019. Unemployment was 3.6% in August 2026, against 3.0% in 2019. Union Electric Co - (MO) is the largest utility serving Jefferson County, one of 3 with territory here. Its residential customers paid an average 12.56¢/kWh in 2024. 233,132 people live here, up 2.7% since 2020, 7th of 115 Missouri counties by population.
Who powers Jefferson County
Utilities with service territory in Jefferson 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% |
| Citizens Electric Corporation - (MO) | Cooperative | Bundled | 24,826 | 15.33¢ | 5% |
| Crawford Electric Coop, Inc | Cooperative | Bundled | 19,775 | 12.78¢ | 16% |
Customer counts, prices and sales shares cover each utility's whole system in the state, not only this county. Commercial sales include data centers.
No operating power plant is located in Jefferson County in the EIA-860M inventory. Its power comes over the grid from plants elsewhere.
Retired since 2019
| Plant | Technology | MW | Year |
|---|---|---|---|
| Rush Island | Coal | 1,242 MW | 2024 |
The Jefferson County labor market
| Industry (2025) | Jobs | Average pay | Concentration vs U.S. |
|---|---|---|---|
| All industries | 49,584 | $52,302 | 1.00 |
| Construction | 4,385 | $74,459 | 1.67 |
| Electrical contractors | 391 | $68,600 | 1.09 |
| Power and communication line construction | 204 | $98,308 | 2.55 |
| Data processing and hosting | 19 | $92,925 | 0.12 |
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 Jefferson County
No data center, local measure or delayed project is on record in Jefferson County. Missouri has 21 local measures on record statewide.
Jefferson County and its neighbors
Of the 6 counties that border Jefferson County, St. Louis 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 |
|---|---|---|---|---|---|---|
| Jefferson County | 233,132 | ▲ 3.4% | — | — | — | — |
| Franklin County | 108,090 | ▲ 0.6% | 2,389 MW | — | — | — |
| Monroe County IL | 34,840 | ▲ 1.4% | 38 MW | — | — | — |
| St. Francois County | 67,809 | ▼ 0.8% | 18 MW | — | — | — |
| St. Louis County | 990,911 | ▼ 3.4% | 34 MW | 648 MW | 7 | — |
| Ste. Genevieve County | 18,689 | ▲ 9.0% | — | — | — | — |
| Washington County | 23,810 | ▲ 2.4% | — | — | — | — |
More of Missouri
Jefferson County, answered from the record
Who provides electricity in Jefferson County, Missouri?
3 utilities have service territory in Jefferson County in the EIA-861 2024 report: Union Electric Co - (MO), Citizens Electric Corporation - (MO), Crawford Electric Coop, Inc. The largest, Union Electric Co - (MO), charged residential customers 12.56¢/kWh on average in 2024.
What county is Arnold, MO in?
Arnold is in Jefferson County, Missouri. About 20,994 people live there (2025 Census estimate).
What county is Festus, MO in?
Festus is in Jefferson County, Missouri. About 14,066 people live there (2025 Census estimate).
Are there data centers in Jefferson County?
The SAVRN Data Center Map has no data center in Jefferson County. The nearest activity on record is next door in St. Louis County.
Is Jefferson County adding jobs?
Employers counted 49,584 jobs in 2025 against 47,947 in 2019 (+3.4%, BLS QCEW). Construction went from 3,906 to 4,385.
Does Jefferson County have a data center moratorium?
No county-level measure is on record for Jefferson County. Missouri has 21 local measures statewide, listed on the state page.