Jail incarceration rates vary widely, but inexplicably, across U.S. cities

Cities jail people at rates that have little to no correlation to their violent crime rates, police budgets, or jail budgets.

By Tiana Herring

Why do some places incarcerate people at much higher rates than others? We considered this question in 2019, when we compared prison incarceration rates across U.S. counties, finding a wide range that loosely correlated to the respective state imprisonment rates. Now, we can do the same for jail incarceration rates. While it’s difficult to find jail incarceration data at the city level, this data is available by county in the Vera Institute of Justice’s Incarceration Trends Database. Using this database, we considered 63 highly populated cities, and calculated the overall jail incarceration rate and pretrial detention rate of each city’s surrounding county. We found that, like prison incarceration rates, jail detention rates vary significantly. But unlike our study of prison incarceration rates, we could find no obvious explanation: neither violent crime rates, local police budgets, nor local jail budgets explained the large differences from city to city. These variations mean that your chances of being put in jail can depend on something as arbitrary as the city you live in.

Jail and pretrial detention rates are important for showing just how deeply mass incarceration is affecting your local community. Jails are the “front door” of the criminal justice system. In 2019 alone, there were more than 10.3 million admissions into U.S. jails. Black and low-income people are disproportionately affected by repeat arrests, and are more likely to be held pretrial simply because they cannot afford bail, perpetuating the cycle of poverty and incarceration. Even short stays in jail can have a major impact on people’s livelihoods, threatening their ability to keep their jobs and housing, and straining familial relationships. This harm is unnecessary, though; as our research has shown, reforms that allow more people to return home pretrial were not associated with rising crime rates in the states, cities, and counties we analyzed.

Varying detention rates defy any logical explanation

We found that jail incarceration and pretrial detention rates vary greatly from city to city. There are some high outliers; Memphis, Tenn., for example, has a total jail detention rate of 491 per 100,000 residents, far above the average jail detention rate across the 63 cities of 225 per 100,000. On the other end of the spectrum, cities like New York and Minneapolis jail fewer than 100 residents per 100,000. Similarly, the pretrial detention rates in St. Louis and Baltimore (395 and 330 per 100,000, respectively) are more than double the average pretrial detention rate for the cities we studied, which was 163 per 100,000. We considered various possible explanations for the drastic differences from city to city, but didn’t find many consistent trends.

Local crime rates don’t consistently explain jail detention rates

First, we used the FBI’s Universal Crime Reporting program data to analyze the cities’ violent crime and total crime rates, to see if high rates of crime correlated with high rates of detention. Memphis, St. Louis, and Baltimore — all of which have notably high detention or pretrial detention rates — do in fact have the three highest violent and total crime rates of the cities for which we were able to obtain data. This pattern isn’t consistent across other cities, though. For example, Charleston, S.C., has some of the highest jail detention and pretrial detention rates, yet its violent crime and total crime rates rank among the lowest of these cities. On the other end of the spectrum, Detroit boasts very low detention rates, but has a relatively high violent crime rate.

It’s also difficult to know how directly violent crime is actually impacting detention rates because other factors likely influence both crime and incarceration. Poverty, addiction, and a lack of social services, for example, could contribute separately to high rates of both crime and jail detention. In fact, detention itself has been shown to increase the odds of future offending, which is counterproductive from a crime rate-defined public safety standpoint.

Local police and jail budgets don’t explain jail rates, either

Next, we explored whether police budgets were correlated with jail and pretrial detention rates. Using the Vera Institute of Justice’s police budget data, we examined the percent of city funds spent on policing and the number of city dollars per resident allocated to the police. Our analysis did not reveal any noteworthy connections between these measures and local jail rates, however.

The Vera Institute of Justice also provides data on the jail budgets in major cities and the number of county dollars spent per resident specifically on jails. Again, we found no strong correlations between jail budgets and jail incarceration rates. The only notable finding is a correlation between changes in jail population and changes in jail budgets since 2011: Cities that reduced their jail budgets (or avoided large increases) also reduced their jail populations more dramatically. While this may not be particularly surprising, it does suggest that cutting jail budgets could help communities reduce the number of people cycling through jails, while freeing up money to be used elsewhere, like schools.

In many places, the effects of bail reform remain to be seen

A number of cities and states included in this analysis, such as Philadelphia and Dallas, have enacted bail reforms in the past few years. However, since most of these changes occurred after 2018 — the most recent year for which the Vera Institute of Justice’s jail detention data are available — the data we used for this analysis do not yet show the effects of those reforms. Ultimately, these reforms should result in reduced pretrial detention rates. Current data show bail reforms have an impact on overall jail detention as well, since the pretrial population makes up about two-thirds of jail populations nationwide.

In New Jersey, for example, pretrial detention populations decreased by 50 percent from 2015 to 2018 - which was just one year after reforms were implemented. Additionally, New Jersey and San Francisco both saw at least 45 percent decreases in their overall jail populations after instituting bail reforms. We hope and expect these reforms (and others implemented more recently) will continue to lower rates of pretrial incarceration in cities and counties across the country.

While there isn’t a clear explanation for why jail incarceration and pretrial detention rates vary so much from city to city, it is clear that too many people cycle through jails each year, and reforms are long overdue. City leaders need to start investing in their communities instead of jails by expanding access to health care and social services, and implementing alternatives to incarceration.

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For footnotes, an appendix table, and more details about our data sources, see the online version of this briefing.