The number of unauthorized immigrants and other noncitizens placed into immigration detention has grown to the highest level in history in the first ten months of President Donald Trump’s second term. It could nearly double in months to come, with the budget for immigrant detention growing by $45 billion over the next three years—at least approximately $14 billion per year—under the One Big Beautiful Bill Act enacted in July. This represents a threefold increase over the $3.9 billion detention budget that U.S. Immigration and Customs Enforcement (ICE) received for fiscal year (FY) 2025, turbocharging what already stood as the world’s largest immigrant detention system. It also means that the annual budget for immigration detention is now on pace to be 62 percent larger than that of the entire federal prison system, which was $8.6 billion in FY 2025.

Detention is key to the Trump administration’s attempt to build a deportation machinery of historic proportions. There were 39,000 detainees in ICE custody when Trump returned to the White House in January 2025, a number that rose to a record 61,000 in late August and could reach as high as 107,000 by January 2026. No prior administration had ever held an average of more than 50,200 people per day in immigration detention (in FY 2019, during Trump’s first term). As of September, detainees spent an average of 44 days in immigration detention, with each detention averaging $152 per day.

To ramp up detention so quickly, the administration has turned to an array of nontraditional facilities, including state-run prisons located in remote areas, soft-sided tent structures, military bases, and even in prisons in other countries. Most importantly, ICE is leaning heavily on private prison contractors, which are playing a critical role in expanding detention capacity and are poised for multibillion-dollar benefits.

In addition to the noncitizens detained by ICE, an unknown number of individuals facing removal have been held in local jails and facilities run by states such as Texas and Florida and other federal agencies including the U.S. Marshals Service and the Federal Bureau of Prisons. The administration is expanding this network of partner state and local jails, which includes facilities labeled by Trump allies with eye-catching names such as Florida’s Alligator Alcatraz and Deportation Depot, Nebraska’s Cornhusker Clink, and the Louisiana Lockup (formally the Louisiana State Penitentiary, also known as Angola Prison).

Immigration detention is civil in nature, and the system’s purpose is to ensure people show up for their removal proceedings and can be deported—in other words be custodial, not punitive.

Yet the Trump administration has leaned into showcasing the harshness of detention, likely as part of its campaign to encourage “self-deportation” or formal voluntary departure. Trump and other top officials have made highly publicized tours through Alligator Alcatraz and similar facilities and the administration is using official social media channels to showcase memes with alligators wearing ICE caps or ASMR videos of shackled detainees being boarded onto deportation flights.  

Meanwhile, there have been persistent, troubling reports of poor conditions in detention facilities across the country, including detainees being given spoiled food and non-potable water, facing severe overcrowding, lack of access to showers and clean clothes, and having harsh lights on 24 hours a day. The number of deaths in ICE detention has risen significantly: at least 23 in FY 2025, according to an American Immigration Council tally of ICE’s news releases, compared to 24 who died over the prior four years combined. The Department of Homeland Security (DHS) denies allegations of poor conditions as “categorically false,” saying detention standards are being met.

Despite the regular rhetoric from White House and DHS officials that detainees are “criminal illegal aliens,” nearly three-quarters of ICE detainees as of September had no criminal conviction, and many of those who did were for minor crimes such as traffic violations.

This article reviews the growth of the U.S. immigrant detention system, including the reliance on private prison companies as well as state and local prisons and jails.

Turbocharging the World’s Largest Immigrant Detention System

The One Big Beautiful Bill Act’s $45 billion for immigration detention represents a threefold annual increase for ICE’s custody operations. This is out of a total $170 billion in the bill to massively increase funding for immigration enforcement, to help meet Trump’s plan of deporting 1 million people per year and further expand border enforcement.

ICE detention had been steadily rising prior to Trump’s return, but has increased by more than one-quarter in FY 2025 (see Figure 1). Still, administration officials appear to want even faster growth, and have shaken up staffing to achieve this result.

Data for FY 2025 include nearly four months of the Biden administration, so the average annual detainee population is likely to increase in coming years, once the full impact of the Trump administration’s approach is felt. The 61,200 people in ICE detention as of August 24, 2025 were more than at any other point on record. With the new funding, the administration plans to add 41,000 detention beds, including in large-scale detention centers and soft-sided facilities that can be rapidly built up or taken down.

Where Are Detainees Kept?

The largest populations of immigrant detainees are in Texas (an average of 13,400 per day as of mid-September), Louisiana (7,500), California (3,800), Georgia (3,000), and Arizona (2,700), according to ICE. Louisiana in particular has become a key player in the system. The state used to have one of the nation’s highest numbers of incarcerated people, but after criminal justice reforms in 2017 the general prison population declined by 8,000 over five years. This coincided with an expansion in immigration detention during the first Trump term, which represented an opportunity for the state to fill its unused prisons and jails. Today, Louisiana has been described as the busiest U.S. deportation hub, illustrated by the detention facility located on the airport tarmac in Alexandria. From January through July 2025, more than 40,000 people transited the facility, either en route to removal from the United States or to one of the eight other ICE facilities in the state.

States, Military Facilities, and Foreign Countries

Immigrant detention is not limited to facilities directly run by ICE. State-run facilities such as the newly built Alligator Alcatraz and the Deportation Depot (formally the Baker Correctional Institution) in Florida serve as detention centers for noncitizens, though it is not always clear whether individuals are held under federal or state authority. People detained in these state facilities are not counted in ICE’s official tally (see more on states’ roles below).

The Lone Star Lockup, located at Fort Bliss, is the largest immigrant detention center in U.S. history, according to DHS. Individuals identified for removal are also detained outside the United States, at military facilities such as the naval base at Guantanamo Bay, Cuba, and the Trump administration has asserted in court that it can legally hold immigrant detainees at any U.S. military facility worldwide. Some noncitizens are also held by foreign governments that have agreed to accept third-country nationals (such as El Salvador and Eswatini), either as a step in their removal elsewhere or for their final destination.

Who Is Detained and How Are They Treated?

Although promising to target only unauthorized immigrants who are “the worst of the worst,” the administration has deemed millions of noncitizens subject to mandatory detention, bypassing the longstanding practice in prior administrations of allowing most people identified for removal to remain free or on alternatives to detention while their case proceeds in immigration court.

The result has been an increase in the arrest and detention of many immigrants who have not been convicted of or charged with any crime. As of September 2025, 71 percent of ICE detainees had no criminal conviction. Of the 25 percent who had a pending criminal charge, most were minor offenses such as traffic violations.

Under long-held interpretations of U.S. immigration law, federal authorities have discretion whether to detain individuals resident in the United States who are deportable.

They are, however, mandated to detain some subsets of deportable noncitizens. Through a July 2025 policy memorandum, ICE vastly expanded the definition of such groups, deeming millions of unauthorized noncitizens subject to mandatory detention, including many who have resided in the country for long periods. 

A Board of Immigration Appeals decision affirmed this position in September, but in dozens of cases federal judges have rejected the new policy, finding that case law and history do not support it. Thus, the legality of this policy remains uncertain, and the question will likely eventually need to be decided by the U.S. Supreme Court.

The Trump administration has also resumed detaining immigrant families apprehended at the border or identified for removal inside the country, a practice ended by the Biden administration in 2021. However, the number of individuals held at ICE’s family detention facilities, known as family staging centers, has remained relatively low compared to the average daily population detained: 358 per day on average in FY 2025.

This figure could grow. As during the first Trump term, the administration has sought to end a 1997 court agreement known as the Flores Settlement, which mandates that children in immigration custody be held in the least restrictive setting possible. That settlement stipulated that the government could not detain children for more than 20 days, and in later interpretations was expanded to apply to families. As before, the Justice Department has argued in court that DHS should be allowed to hold families for longer. In August, a federal judge denied that request. But the One Big Beautiful Bill Act included a provision permitting the indefinite detention of families awaiting a decision on their removal case. Experts have deemed this an attempt to supersede the Flores Settlement, and it will likely be challenged in court.

Conditions in Detention

Many detainees face challenges finding legal representation and keeping in touch with their family and community support systems, partly as result of the government’s use of detention facilities in remote locations as well as increased fast-track deportations. These limitations are exacerbated by the recent practice of transferring detainees between facilities multiple times within a short timeframe.

Unlike in the general prison system, standards for ICE detention are not codified in law and therefore are nonbinding; compliance varies by facility. As such, there is little government oversight and limited public access and information.  

Press reports and detainee accounts often describe poor conditions. Common complaints include overcrowding, low amounts of food and in poor quality—sometimes even expired—poor air quality, lack of clean water, extreme temperatures, and inadequate bedding. Serious allegations of neglect have also surfaced, including delayed medical care, as well as verbal and physical abuse by detention staff.

Detainees also face anxiety from the uncertain length of detention and overall opacity of the process. Rising arrests will likely increase the massive backlogs in immigration courts, further lengthening detention times. As of September 2025, average ICE detention was about 44 days, with the highest average (111 days) at the Golden State Annex in McFarland, California.

Research has shown that prolonged detention can cause detainees to abandon their claim for asylum or other relief from deportation, opting instead to formally voluntarily depart as a way to leave detention sooner. Some speculate that one of the Trump administration’s aims is to increase these voluntary departures, which are registered in immigration court, as well as unofficial “self-deportations” by unauthorized immigrants who fear being detained. As of early October, DHS data obtained by ProPublica showed that about 25,000 noncitizens had reported their self-deportation via the government’s CBP Home app, which permits receipt of a $1,000 payment upon return and a free flight home for the individual and family members.

U.S. officials have vigorously denied that poor or abusive conditions exist in detention facilities. However, the government has provided little transparency or oversight into the situation inside detention centers. Several congressional Democrats have sued the government after being denied entry, sometimes by force, into immigrant detention facilities to conduct oversight.  

The Role of the Private Sector

Private companies have long been drawn to immigration detention and play a greater role in it than in the general prison system. As of early 2025, close to 86 percent of immigrant detainees were held in privately run facilities, compared to less than 10 percent of the overall U.S. incarcerated population.

To manage the rise in immigrant detention under the Clinton administration, the federal government during the 1990s struck contracts with private companies to provide low-security detention spaces. Two of the largest companies in this sector were—and remain—GEO Group and CoreCivic, which are currently valued around $4 billion and $2.2 billion, respectively. These contractors also run private facilities in the general U.S. prison system, but immigrant detention represents a significant share of their revenues. Records show both companies submitted bids to develop more detention facilities under the new federal funding.

For the private prison industry, immigrant detention represents a profit opportunity on multiple fronts. In addition to government funds for housing individuals, the companies can profit from detainees themselves, who must pay to make phone calls or obtain basic necessities from the generally company-owned commissaries, which sell goods considerably above average market price. Detainees receive pay as low as $1 per day running some of the facilities’ essential services, including food management and laundry. While these jobs are described as voluntary, many detainees have no other option to earn money to supplement their rations.

The Growing Involvement of State and Local Actors

In addition to rapidly growing federal immigrant detention, the Trump administration is relying on state partners. Building or offering existing bed space and accepting transfers from other jurisdictions has become an easy way for Republican state leaders to curry favor with the administration.

For rural areas in need of economic revival, immigrant detention also presents an economic opportunity. In addition to gaining political capital, local governments often receive commissions from contracts with private prisons, linked to commissary sales. These and other revenue streams can be important amid federal cutbacks. In the last decade, close to 70 percent of newly constructed immigration detention facilities were in rural areas.

The old real estate adage—location, location, location—also matters here. Many newly tapped detention facilities and hubs are located in circuit court jurisdictions that are regarded as among the most sympathetic to the administration’s position on immigration enforcement, meaning noncitizens’ chances of being released are low and their chances of being deported are high.

Immigrant Detention across Republican and Democratic Administrations Alike

The U.S. immigration detention system dates back at least to the 1891 Immigration Act, which solidified the role of the federal government in immigration enforcement. But the system as it currently exists was built largely since the late 1980s and 1990s, as the federal government criminalized drug-related offenses and introduced mandatory minimum sentences, among other measures meant to address crime. The result was a dramatic increase in incarceration generally, which also affected immigrants. Notably, the Illegal Immigration Reform and Immigrant Responsibility Act of 1996 expanded the definition of deportable offenses, thereby increasing the number of lawfully present noncitizens who could be detained for removal.

Congress’s use of appropriations measures to set a minimum bedspace capacity, commonly known as the bed mandate, represents a unique feature of the U.S. immigration detention system. This policy was rooted in national security concerns and has its origins in the Intelligence Reform and Terrorism Prevention Act of 2004. Critics charge it with incentivizing arrests, especially of low-priority removable noncitizens.

Congress formally established the bed mandate with its FY 2009 appropriations bill, requiring the agency to maintain 33,400 detention beds per day. The minimum number of beds remained roughly the same throughout the first Trump term and was raised to 41,500 in FY 2024, under the Biden administration. While the congressional mandate has not changed since then, detention has significantly increased. Homeland Security Secretary Kristi Noem has stated ICE should aim to hold 100,000 individuals daily, and the agency is well on pace to meet that goal. By comparison, there were approximately 155,000 federal inmates in prison as of October 23, 2025.

What Comes Next After Rapid Growth?

With the help of Congress, the Trump administration is building a vast immigration detention system. Increased detention is upending the lives of many immigrants, their families, and communities.

Questions remain about the long-term consequences of the build-up. If the system’s shock and awe encourage unauthorized immigrants to self-deport or seek voluntary departure, and if incoming border encounters remain at historical lows, there will be less need for immigration detention space in the future. What then will happen to the new facilities? Will they be closed, eliminating jobs and economic boon to local communities? Or could they be repurposed?

The ramifications of the recent changes are unknown, but the speed at which the system is being expanded suggests that there will likely be unforeseen repercussions that government officials, communities, and immigrants themselves will need to grapple with in years ahead.

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