Mercer County
Its jail, located in Aledo, has a capacity of 102.
Mercer County has a population of 15,292 and is classified by the U.S. Department of Agriculture as “Metro - Counties in metro areas of 250,000 to 1 million population”.
Annual inspections
Between 2017 and 2025, the Mercer County jail has failed five of nine Illinois Department of Corrections inspections.
Inspectors cited violations to “Supervision” regulations most often, bringing it up in three of those failed inspections.
| Year | Result | Violations cited |
|---|---|---|
| 2025 | Noncompliant |
|
| 2024 | Noncompliant |
|
| 2023 | Noncompliant |
|
| 2022 | Compliant | — |
| 2021 | Compliant | — |
| 2020 | Noncompliant |
|
| 2019 | Noncompliant |
|
| 2018 | Compliant | — |
| 2017 | Compliant | — |
Each violation links to the standard it cites in the Illinois County Jail Standards. Years link to the full inspection report for that year on the IDOC website.
Extraordinary or unusual incidents
Mercer County reported 2 extraordinary or unusual incidents at its jail between 2019 and 2025 — 1.3 per 10,000 residents, the 80th highest rate of the 92 Illinois counties with a jail.
Among the 36 metropolitan counties it is 31st; those counties report a median of 8.3. The median for every county with a jail is 7.
A county reporting less could indicate lower incident rates or lower reporting rates.
Incidents per 10,000 residents
Mercer CountyMetropolitan counties Every other county with a jail
Most frequent categories
- Suicide attempt2
- Serious injury2
- Suicide1
A single report can fall into more than one category.
Reported incidents by year
Deaths in custody
No deaths in custody were identified at the Mercer County jail.
Illinois Answers withheld the names of some of the deceased at the request of their families.
Data compiled 2026-09-15. Methodology.