The Bureau of Justice Statistics published its Jails Report Series: 2024 Preliminary Data Release on December 2, 2025, reporting that local jails held an estimated 657,500 persons in custody at midyear 2024 and logged 7.9 million admissions between July 1, 2023 and June 30, 2024, per BJS. The release is the first statistical picture of the nation's roughly 2,800 local jails for 2024; final figures will follow in the annual Jail Inmates in 2024 statistical tables.
The numbers described here are preliminary and subject to revision in the final tables; this article explains the statistics and the process behind them.
What do the preliminary figures show?
Per BJS, the midyear 2024 population estimate of 657,500 people held in local jails counts persons confined in facilities run by counties and municipalities — a population that turns over rapidly. The 7.9 million admissions figure captures that churn: most jail stays are measured in days, and a large share of those admitted are being held pending charges, meaning they have been neither convicted nor acquitted of anything.
Jail data therefore describes pretrial detention as much as punishment. The gap between 657,500 people in custody and 7.9 million admissions in a single year is the clearest statistical portrait of how transient jail incarceration is.
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Why publish preliminary numbers at all?
BJS moved its jail statistics to a two-step release in recent years: a preliminary web release a few months after the reference period, then final statistical tables once every jurisdiction's Annual Survey of Jails response is reconciled. The preliminary step lets researchers and policymakers see direction of travel — whether populations are rising or falling — about a year ahead of the definitive tables, per the agency's publication notes.
The trade-off is stability. Preliminary estimates can shift when late-reported facilities or reclassified counts arrive, which is why BJS labels the figures as such and why careful citation includes both the release date and the word preliminary.
How does jail data differ from prison data?
Prisons hold people sentenced to more than a year, mostly under state or federal authority; jails hold people awaiting trial or serving short sentences, mostly under local authority. Per BJS's prior published counts, the state and federal prison population stood near 1.2 million, roughly double the jail population — but jails process far more people annually because of turnover.
Readers comparing the two should also note timing conventions: prisons are counted at year-end, jails at midyear, which complicates casual comparisons but serves each system's administrative calendar.
What happens next?
BJS's forthcoming Jail Inmates in 2024 tables, listed on the agency's publication schedule, will finalize population, admission, demographic, and conviction-status counts, and the 2025 midyear survey is already in the field. When the final tables arrive, the December 2025 preliminary figures should be replaced in citations — the record as of the later release date governs.