This article was originally published by Prison Policy Initiative as “New data and visualizations spotlight states’ reliance on excessive jailing,” authored by Emily Widra

One out of every three people behind bars is being held in a local jail, yet jails get almost none of the attention that prisons do. In 2017, we published an in-depth analysis of local jail populations in each state: Era of Mass Expansion: Why State Officials Should Fight Jail Growth. We paid particular attention to the various drivers of jail incarceration — including pretrial practices and holding people in local jails for state and federal authorities — and we explained how jails impact our entire criminal legal system and millions of lives every year. In the years since that publication, many states have passed reforms aimed at reducing jail populations, but we still see the same trends playing out: too many people are confined in local jails, and the reasons for their confinement do not justify the overwhelming costs of our nation’s reliance on excessive jailing.

People cycle through local jails more than 7 million¹ times each year and they are generally held there for brief, but life-altering, periods of time.² Most are released in a few hours or days after their arrest, but others are held for months or years,³ often because they are too poor to make bail.⁴ Fewer than one-third of the 663,100 people in jails on a given day have been convicted⁵ and are likely serving short sentences of less than a year, most often for misdemeanors. Jail policy is therefore in large part about how people who are legally innocent are treated, and how policymakers think our criminal legal system should respond to low-level offenses.

Figure 1. The frequent practice of renting jail cells to other agencies makes it difficult to draw conclusions from the little data that is available. This update to our 2017 report offers an updated analysis of national data to offer a state-by-state view of how jails are being used and we continue to find that pretrial populations continue to drive jail growth across the country. The data behind this graph is in Appendix Table 1.

More than 460,000 people are currently detained pretrial — in other words, they are legally innocent and awaiting trial. Many of these same people are jailed pretrial simply because they can’t afford money bail, while others remain in detention without a conviction because a state or federal government agency has placed a “hold” on their release.

Pretrial detention disproportionately impacts already-marginalized groups of people:

• Low income: The median felony bail amount is $10,000, but 32% of people booked into jail in the past 12 months reported an annual income below $10,000.
• Black people: 43% of people detained pretrial are Black. Black people are jailed at more than three times the rate of white people.
• Health problems: 40% of people in jail reported a current chronic health condition. 18% of people booked into jail at least once in the past 12 months are not covered by any health insurance.
• Mental illness: 45% of people booked into jail in the past 12 months met criteria for any mental illness, compared to only 30% of people who had not been jailed.
• Experiencing homelessness: While national data don’t exist on the number of people in jail who were experiencing homelessness at the time of their arrest, data from Atlanta show that 1 in 8 city jail bookings in 2022 were of people who were experiencing homelessness.
• Lesbian, gay, or bisexual: 15% of people booked into jail in the past 12 months identify as lesbian, gay, or bisexual, compared to 10% of people not booked in the past year.

This confinement creates problems for individuals on a short-term basis and also has long-term effects. Research in different jurisdictions has found that, compared to similarly-situated peers who are not detained, people detained prior to trial are more likely to plead guilty, be convicted, be sentenced to jail, have longer sentences if incarcerated, and be arrested again. And these harms accrue quickly: being detained pretrial for any amount of time impacts employment, finances, housing, and the well-being of dependent children. In fact, studies have found that pretrial detention is associated with a decreased likelihood of court appearance and an increased likelihood of additional charges for new offenses. There is no question that wholesale pretrial detention does far more harm than good for an increasing number of people and communities.

State and federal agencies pay local jails a per diem (per day) fee for each person held on their behalf. For example, in 2024, the state Department of Public Safety and Corrections (prison system) pays local jails in Louisiana $26.39 per person per day, and more than 14,000 people in the Department’s custody were in local jails in 2022. The fees paid by different agencies to confine people in local jails range and depend on the contract between agencies: In 2023, the per diem rate negotiated between Daviess County, Kentucky and the U.S. Marshals Service increased from $55 to $70 per person per day. These per diem fees can rack up quickly: in fiscal year 2021, the U.S. Marshals Service paid North Carolina counties more than $31 million for jail holds, while the Louisiana Department of Corrections spent more than $123 million on their “local housing of adult offenders” program.

In 28 states and the District of Columbia, more than 10% of the jail population is being held on behalf of a state or federal authority. This both skews the data and gives local jail officials a powerful financial incentive to endorse policies that contribute to unnecessary jail expansion. Local sheriffs — who operate jails that are rarely filled to anywhere near their total capacity with people held for local authorities — can pad their budgets by contracting out extra bed space to federal and state governments. To be sure, sharing some jail capacity can be a matter of efficiency: for example, if one county’s jail is occasionally full, borrowing space from a neighboring county may be better than building a larger jail. And, in some states — like Missouri — state law requires that local jails agree to hold people for state or federal agencies. But the systematic renting of jail cells to other jurisdictions — while also building ever-larger facilities in order to cash in on that market⁶— changes the policy priorities of jail officials, leaving them with little incentive to welcome or implement reforms.

Fight jail expansionsWhat to do when your county proposes a bigger jail.

In our 2017 report, we found this phenomenon was most visible in Louisiana, where the state largely outsourced the construction and operation of state prisons to individual parish (county) sheriffs.⁷ The most recent data suggests that as of 2022, Louisiana, Kentucky, and Mississippi stand out as the worst offenders. In all three states, at least one-third of the state prison population is actually held in local jails (53% in Louisiana, 47% in Kentucky, and 33% in Mississippi).⁸

Another major consumer of local jail cells is the federal government, starting with the U.S. Marshals Service, which rents about 26,200 jail spaces each year — mostly to hold federal pretrial detainees in locations where there is no federal detention center. In the District of Columbia, South Dakota, New Hampshire, and New Mexico, more than 15% of the statewide jail population was actually held for the U.S. Marshals Service in 2019. Meanwhile, Immigration and Customs Enforcement rents about 15,700 jail spaces each year for people facing deportation.⁹ In 2019, New Jersey stood out with 16% of the statewide jail population held for immigration authorities, followed by Mississippi (10%).

We should note there is significant geographic variation in just how much of a jail’s population is held for other authorities: more than a quarter of people in rural jails were held for state, federal, or American Indian and Alaska Native tribal governments in 2019, compared to only 11% of people in urban jails.¹⁰ The distribution also varies by state, as each has different levels of “excess” jail capacity, and federal officials have specific needs in different parts of the country.

The practice of holding people in local jails for other authorities carries significant personal, social, and fiscal costs, often exposing detained people to the harms of incarceration for longer periods of time than they would be otherwise. Jails are not designed to hold people for any significant period of time; they lack sufficient programming, services, and medical care to house people for months or years.¹¹ This practice also contributes to jail overcrowding, which fuels jail construction and expansion in turn. As scholars Jack Norton, Lydia Pelot-Hobbs, and Judah Schept succinctly put it: “When they build it, they fill it, and counties across the country have been building bigger jails and planning for a future of more criminalization, detention, and incarceration.”

Updated state-specific graphics

In 2017, we argued that if lawmakers want criminal legal system reform, they must pay attention to jails. Years later, this remains true. To help state officials and state-level advocates craft reform strategies appropriate for their unique situations, this report offers updated data and state-specific graphs on conviction status, as well as changes in incarceration rates and populations in both prisons and jails.