Slightly under 1.5 million people were in prison at the end of 2017, a population that if gathered in one place would be one of the largest cities in the country. Still, this was a decrease of 1.2% from 2016, and a nearly 8% drop from the peak of prison population in 2009. County and city jails held around 750,000 inmates in mid-2017.
Combined, this would make the United States by far the world’s leader in incarceration according to data collected by the Institute for Criminal Policy Research at Birkbeck, University of London, though it is unclear exactly how many people are held in detention in China, the country with the second highest count.
The incarceration rates for people in prison (those serving sentences after conviction) and jail (those awaiting trial or sentencing, or otherwise being held in short-term detention) have also decreased by more than 10% over the past 10 years.
The decline has been markedly uneven. A drop in the federal prison population accounts for a third of the year-over-year decline, and while some states have significantly reduced their prison populations in recent years, others continue to set records for the number of people they are keeping locked up. Given that crime rates have fallen across the nation over the past decades, this unevenness is almost entirely because of policy changes and court orders.
“Crime rates have been declining for 25 years now pretty much across the board,” said Marc Mauer, the executive director of the Sentencing Project, a group that advocates for improvements to the criminal justice system. “One might ordinarily think this should have led to a substantial reduction in the prison population.”
Instead, he said, “what we see is that a moderate number of states have achieved substantial reductions of 30 percent or more, but most states have only experienced a very modest decline and some states have still been increasing their population.”
While there has been bipartisan talk of prison reform in recent years, with laws to curb the enormous prison population passing in states controlled by Democrats and Republicans alike, a smaller number of states account for the biggest decreases.
California was ordered by the U.S. Supreme Court in 2011 to reduce its overcrowded prisons by 30,000 inmates. But other states with big drops, including New Jersey, New York and Connecticut, pushed their own policy changes, such as reclassifying felonies as misdemeanors, giving more discretion to sentencing judges and changing guidelines for granting parole.
The numbers also show that a dramatic reduction in the prison population is unlikely if changes address only nonviolent offenses. At the end of 2016, the report shows, more than half of state prisoners had been convicted of violent offenses.
The statistics released on Thursday also show that the nature of the prison population has changed in significant ways. While the racial disparity among men remains stark, with black men serving prison sentences at almost six times the rate of white men, the disparity among women has considerably narrowed.
In 2000, black women were incarcerated at six times the rate of white women, but in 2017, black women were imprisoned at less than double the rate of white women. And while the number of white women in prison has increased by more than 40% since the turn of the century, the number of incarcerated black women has dropped by nearly half.
This article originally appeared in The New York Times.