NORTHAMPTON, Mass. — A new report from the Prison Policy Initiative analyzing the most recent national incarceration data finds that the recent rise in the number of people behind bars in the United States was largely driven by immigration detention.
The report, Mass Incarceration: The Whole Pie 2026, states that the number of people held in detention by U.S. Immigration and Customs Enforcement increased by approximately 25,200 people between 2025 and 2026, marking a 58 percent increase.
Researchers stated that this rise in immigration detention accounts for nearly all of the growth in the total incarcerated population over the past year.
Across federal agencies responsible for immigration-related confinement, including the Federal Bureau of Prisons, the U.S. Marshals Service and the Office of Refugee Resettlement, the number of people detained for immigration-related reasons has increased by 32 percent since last year.
The report also found that other incarceration trends moved in the opposite direction.
In 2024, the number of people held in city, county and regional jails decreased by roughly 17,000.
Additionally, about 10,000 fewer people were incarcerated for federal crimes in 2026 compared with 2025.
The press release stated that, while prison and jail populations have remained relatively steady, immigration detention has expanded rapidly.
It also noted that the number of facilities holding individuals for ICE increased by 65 percent over the past year.
In addition to incarceration data, the report includes a section addressing common misconceptions about mass incarceration and crime, along with an analysis showing how minor offenses can escalate into time behind bars.
It also analyzes the broader correctional system, noting that when probation and parole are included, more than 5 million people in the United States remain under some form of correctional control.
Furthermore, the report estimates that the total financial cost of mass incarceration in the United States reaches approximately $445 billion each year, including government spending and financial burdens placed on the families of incarcerated individuals.
These costs include court expenses, law enforcement operations, incarceration facilities and the long-term financial consequences incarceration can create for many individuals attempting to reenter society.
Researchers argued that while some traditional incarceration measures have declined, the rapid increase in immigration detention is reshaping the overall scale of the U.S. carceral system.
Analysts also note that immigration detention often operates through a separate legal framework from the criminal legal system; however, it contributes significantly to the total number of individuals held in confinement across the country.
The findings suggest that immigration policy is increasingly intertwined with the broader system of incarceration in the United States.
As immigration detention expands while other incarceration rates stabilize or decline, advocates and policymakers may face growing debates over how enforcement policies, detention infrastructure and federal priorities are shaping the future scope of the nation’s carceral system.
Some researchers warn that, without policy changes, immigration detention could continue to drive future increases in incarceration even as other forms of imprisonment remain stable.
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