How to Look Up St. Clair County Jail Population Data
St. Clair County does not publish a single jail population dashboard. The closest official county data point lives in the Sheriff Jail line of the annual budget, posted by the County Auditor. The 2025 Annual Budget Appropriations file is the document to pull for the current jail funding number. The Sheriff Corrections page covers the current-custody inmate lookup and the way the Sheriff describes day-to-day jail operations, but it does not publish a capacity number or an average daily population figure. The Sheriff's elected official profile is where the official acknowledgement of jail overcrowding and the need for jail expansion lives.
Outside the county, federal and nonprofit researchers track jail populations at the state and national level. The Bureau of Justice Statistics releases annual jail inmate reports. The Vera Institute hosts a county-level incarceration trends dataset. The Prison Policy Initiative publishes state profiles with jail and prison breakdowns. None of these outside sources are county-published, and the rates and counts they show should be read as research figures, not as a county press release. A reader looking for St. Clair County jail population data uses the county budget for funding context, the Sheriff's pages for operational context, and the outside research datasets for state and national comparison. Update timing also varies. Budgets are annual. BJS national jail reports are annual. The Vera county dataset is updated as new federal data becomes available.
St. Clair County Jail Capacity Overview
The county runs two custody buildings. The adult jail at 700 N. 5th Street in Belleville is the main facility under the Sheriff's Department. The Detention Center at 9006 Lebanon Road in Belleville handles juveniles ages 10 to 16 and is run by Probation and Court Services, not the Sheriff. The harvested official sources for both buildings do not publish a rated capacity number or a current head count. A capacity figure is treated as not located rather than estimated.
| Facility | Address | Population Served | Rated Capacity (Official) |
|---|---|---|---|
| St. Clair County Jail | 700 N. 5th Street, Belleville, IL 62220 | Adult pretrial and short-sentence custody | Not published in harvested official sources |
| St. Clair County Detention Center | 9006 Lebanon Road, Belleville, IL 62223 | Juveniles ages 10 to 16 | Not published in harvested official sources |
Sheriff Rick Watson has publicly cited jail overcrowding and the need for jail expansion as priorities of his administration on the Sheriff's elected-official profile. A county meeting minute search result from late 2025 also flags a "Jail Management Information System" item and an "Over Capacity" reference. Both are signals that the building runs near or above design limits in practice, even when an exact bed number is not in the published record. The point of the capacity overview is to read the official signal, not to invent a head count.
Average Daily Population
An average daily population, or ADP, is the mean number of people held in a jail across a year. For St. Clair County, the official sources reviewed for this page do not publish an ADP figure for the Belleville jail. The Sheriff's pages cover the inmate lookup and the corrections function. The county budget covers the jail funding line. Neither document states an ADP.
National jail ADP data does exist. The Bureau of Justice Statistics publishes annual jail inmate counts with state-level breakdowns. The Vera Institute publishes a county-level dataset built on federal jail data. A reader who needs an ADP-style figure for St. Clair County uses those outside sources as research context. Any number quoted from those sources stays labeled as research data, not as a county count. The right next step for a hard local ADP figure is a direct request to the Sheriff's Corrections division at the jail phone line, since corrections staff track daily counts as part of normal jail operation even when the count is not posted online.
Demographic Breakdown
Jail demographic data covers gender, race, age, and charge type for the people held in a facility. The Sheriff's harvested pages for St. Clair County do not publish a demographic breakdown of the jail population. The inmate lookup is an individual-search tool. It does not aggregate the roster into a gender, race, or age table.
Demographic context at the state level is available through Illinois state-prison reports and through outside research from the Vera Institute and the Prison Policy Initiative. Those reports show how Illinois jails and prisons compare to the national mix on race, gender, and age. The numbers in those reports describe the state and the national picture, not the St. Clair County jail in particular. For a Belleville-specific demographic table, the source is the Sheriff's Corrections division or a county board record that publishes a snapshot. Until that snapshot is published, the demographic split for the county jail stays on the research-gap list, and any percent number for the local jail should be treated as not yet sourced rather than estimated for the page.
Pretrial vs Sentenced Population
Most county jails hold a mix of people. Some are waiting for a court date and have not been convicted. Some are serving a short sentence after a conviction. The split between pretrial and sentenced custody is one of the most studied jail data points. National research from the Bureau of Justice Statistics and the Vera Institute shows that pretrial detention drives a large share of the typical county jail population in the United States.
| Custody Status | What It Means | St. Clair County Figure |
|---|---|---|
| Pretrial | Held while a case is pending, no conviction yet | Not published in harvested official sources |
| Sentenced | Convicted and serving time under a court order | Not published in harvested official sources |
| Holds and transfers | Held for another agency or awaiting transfer to state custody | Not published in harvested official sources |
For Illinois as a whole, statewide jail and prison reports describe how the cash bond reform under the Pretrial Fairness Act has changed the pretrial picture across counties since 2023. State and national context tells the structural story. The county-specific split, by share of beds used, is the data point that the harvested Sheriff pages do not publish. For a current local split, the Sheriff's Corrections division is the office to ask, and the State's Attorney and Circuit Clerk file numbers are the court-side records that pair with the jail count.
Misdemeanor vs Felony Population
Illinois divides adult criminal cases into felonies and misdemeanors. Felonies are filed with case-number prefixes such as CF or DT in felony DUI cases. Misdemeanors use prefixes such as CM and TR for ordinance and traffic-related charges. The county Circuit Clerk handles those filings. The jail itself does not publish a misdemeanor-versus-felony share of the inmate count in the harvested Sheriff pages.
That split can be estimated by pulling case-number prefixes from the Circuit Clerk court file for everyone booked in a given period, but that is a research project, not a Sheriff dashboard. The Sheriff's roster shows the person and the booking. The Circuit Clerk's docket shows the case number and the charge level. Together they tell the misdemeanor-versus-felony story. Apart, neither one gives the count.
Note: A booking can appear on the inmate lookup before the matching case number posts on the Circuit Clerk side, so a same-day count by charge level is harder than it looks.
Mental Health and Medical Population
Jails across the country hold a large share of people with mental health needs and chronic medical conditions. Illinois case files use the MH category prefix for mental health cases, which sit on the civil side of the Circuit Clerk file and are distinct from the criminal docket. That is a court category, not a jail bed count. The Sheriff's Corrections pages do not publish a daily count of inmates in mental health treatment, on suicide watch, or in medical housing.
National research is the only available context. The Bureau of Justice Statistics has published jail inmate mental health reports across multiple years. The Prison Policy Initiative covers Illinois on a state profile page with notes on health, race, and offense type. Those reports give the national and state lens. A county-level count of mental health and medical custody at the Belleville jail is again on the research-gap list and would have to come from the Sheriff's Corrections division or a county health department record.
National and State Context
Outside research is the main lens for placing St. Clair County in a national jail incarceration picture. The Bureau of Justice Statistics is the federal agency that publishes the annual jail inmates report and the prisoners-in-the-United-States series. BJS data is the standard reference for how many people sit in local jails on a given day, what share are pretrial, and how jail counts shift year over year. 
The Bureau of Justice Statistics site is the federal data hub for jail and prison counts used in the state and national context for St. Clair County.
For an Illinois-focused view, the Prison Policy Initiative Illinois profile is a research source that places state jail and prison counts inside national comparisons. The profile covers Illinois jail counts, state prison counts, race breakdowns, and bail/bond trends. It pulls from the federal Bureau of Justice Statistics and the United States Census. 
The Prison Policy Initiative Illinois profile is the research source for the state-level jail context that wraps around the St. Clair County numbers.
| Level | Source | What It Shows |
|---|---|---|
| St. Clair County | County budget Sheriff Jail line and Sheriff Corrections page | Funding trend and current-custody lookup; no aggregate count |
| Illinois | Prison Policy Initiative Illinois profile and Illinois Department of Corrections | State jail and prison totals, race breakdowns, pretrial share |
| National | Bureau of Justice Statistics jail inmates report | National jail counts, rate per 100,000 residents, pretrial share |
A county-versus-state-versus-national rate per 100,000 is the standard way researchers compare jail incarceration. The state and national rates are reported in BJS and Prison Policy figures. A St. Clair County rate per 100,000 is not separately published by the county. Until a county-published rate is on the record, the local entry on that comparison stays open. The official figures from BJS and Prison Policy Initiative are the right numbers to read first.
Population Trends Over Time
Direct head-count trend data for the Belleville jail is not in the harvested official sources. What the county does publish is a multi-year funding trend in the Sheriff Jail line of the annual budget. Funding is not the same number as population. A budget line goes up for many reasons, including staff costs, contracts, and capital. Still, a sustained increase in the jail line is an official signal worth tracking.
| Budget Year | Sheriff Jail Appropriation | Change from Prior Year |
|---|---|---|
| 2024 | $7,755,551 | Prior-year baseline for the 2025 comparison |
| 2025 | $8,560,123 | Up $804,572, a 10.37% increase |
The 2025 increase lands inside a broader justice-system spend that the county lays out in the same budget. Related lines for 2025 include $5,056,010 for Sheriff Patrol, $2,597,664 for the State's Attorney, $1,646,622 for the Circuit Court Clerk, $1,080,608 for the Public Defender, $883,946 for Probation, and $740,033 for Sheriff Administration. The total picture is a county justice system under real fiscal pressure. Sheriff Watson's elected-official profile lists addressing jail overcrowding and the need for jail expansion as stated priorities, which lines up with the budget signal. A future-year extract from the 2026 county budget would close the trend out, but the 2024 to 2025 jump is the firm data point on the record today.
Searching for St. Clair County Inmate Records by Name
This page covers aggregate jail population data, not individual custody lookups. To search the Sheriff's live jail roster by last name, first name, or booking number, use the St. Clair County inmate records page, which is built around the Sheriff's official lookup at inmates.stclaircounty.org.
Where the Data Comes From
The sources used for St. Clair County jail population context split into county documents and outside research datasets. Each source covers a different part of the picture. None of them, on its own, gives a single capacity-plus-population number for the Belleville jail.
- County budget appropriations from the County Auditor. The Sheriff Jail line and related justice-system lines show year-over-year funding.
- The Sheriff Corrections page at stclaircountyil.gov. Covers the current-custody inmate lookup and operating notes about the jail.
- The Sheriff's elected official profile. The source for the official statement on jail overcrowding and the need for jail expansion.
- The federal Bureau of Justice Statistics. National annual jail and prison counts, rates per 100,000, and pretrial share.
- The Vera Institute incarceration trends work. County-level jail incarceration trend research built on federal data.
- The Prison Policy Initiative Illinois profile. Illinois-focused jail and prison context with race and pretrial breakdowns.
The county budget is an annual document. The Sheriff's pages are operational. The federal and nonprofit datasets are research products. A reader who wants the full picture pulls from all three layers. The local numbers anchor the county. The state and national numbers frame the comparison. The official caveat from the Sheriff still applies. The inmate lookup does not warrant accuracy, timeliness, or completeness, and the population-side data on the research datasets is reported on a lag.