Immigration detention in the United States

Based on Wikipedia: Immigration detention in the United States

The United States runs the largest immigration detention system on Earth. That's not a boast or a criticism—it's simply a fact, documented by the Global Detention Project, an organization that tracks how countries around the world handle migrants. As of 2020, over two hundred separate facilities across the country hold people whose only crime, in many cases, is crossing a border without the right paperwork.

But how did we get here? And what does it actually mean to be "detained" in the immigration system?

The Numbers Tell a Story

Let's start with scale. During the 2023 fiscal year, more than 273,000 people were booked into the custody of Immigration and Customs Enforcement—the agency most people know as ICE. On any given day that year, roughly 28,000 non-citizens sat in detention. By the end of the fiscal year, that number had climbed to nearly 37,000.

Children represent a separate category entirely. About 7,000 immigrant children are housed in facilities overseen by the Office of Refugee Resettlement, which operates under the Department of Health and Human Services rather than the enforcement-focused Department of Homeland Security. In fiscal year 2023 alone, nearly 119,000 unaccompanied children were referred from the Department of Homeland Security to be processed into this system.

These aren't abstract statistics. Each number represents a person sitting in a facility, waiting to learn whether they'll be allowed to stay or be sent back to wherever they came from.

From Castle Clinton to Guantanamo: A Brief History

Immigration detention in America is nothing new. It dates back to 1855, when Castle Clinton—a circular stone fort at the southern tip of Manhattan—served as the nation's first immigrant processing center. If you've ever strolled through Battery Park, you've walked past it. Today it's a ticket booth for the Statue of Liberty ferry. Back then, it was where America decided who got in.

The more famous Ellis Island took over in the 1890s and processed millions of European immigrants through the early twentieth century. During World War II, it shifted purpose, becoming a holding facility for foreign nationals considered potential threats. By the 1950s, though, Ellis Island had fallen quiet.

The modern era of immigration detention really began in the 1980s. When Haitians started arriving on boats, fleeing both economic collapse and political violence, President Ronald Reagan established a program to intercept them at sea—literally stopping and searching vessels suspected of carrying undocumented migrants before they could reach American shores.

The numbers quickly overwhelmed the system. President George H.W. Bush tried to find regional solutions, and the United Nations High Commissioner for Refugees arranged for several countries—Belize, Honduras, Trinidad and Tobago, and Venezuela—to temporarily shelter Haitian refugees. It wasn't enough. By November 1991, the Coast Guard was forcibly returning Haitians to the very country they'd fled.

Then came Guantanamo.

Long before it became synonymous with the War on Terror, the U.S. naval base in Guantanamo Bay, Cuba served as a massive processing center for Haitian asylum seekers. The Coast Guard brought them there, and officials pre-screened their asylum claims on Cuban soil—technically outside U.S. legal jurisdiction.

The Architecture of Modern Detention

The system as we know it today took shape in 2003, when Immigration and Customs Enforcement was created as part of the massive post-9/11 reorganization that established the Department of Homeland Security. ICE absorbed functions previously scattered across multiple agencies and became the primary enforcer of immigration law inside the country.

Within ICE, the Office of Enforcement and Removal Operations—called ERO—handles the actual detention process. Their official mission statement reads like bureaucratic poetry: they carry out "the immigration enforcement process, including the identification, arrest, detention and removal of noncitizens who are subject to removal or are unlawfully present in the U.S."

What does that look like in practice?

When someone is detained, they receive what's called an Alien Registration Number, or A-number—assuming they don't already have one from previous legal immigration status. Then they're sent to wait. That waiting happens in a patchwork of different facilities: federal detention centers, state prisons, county jails, private facilities run by corporations, juvenile detention centers, and shelters.

ICE operates eight of its own facilities directly, spread from Puerto Rico to California. These are called Service Processing Centers—government-speak for detention facilities. But the majority of detained immigrants don't end up in federal facilities at all. They're held in state and local jails that have contracts with ICE.

Private companies play an enormous role too. ICE contracts with seven corporations to run detention facilities in places like Aurora, Colorado; Houston, Texas; and Elizabeth, New Jersey. By the end of fiscal year 2007, the immigration detention system comprised 961 different sites. It has only grown since.

How People End Up Detained

There are several paths into immigration detention, and understanding them helps clarify what kind of system this actually is.

The most straightforward route is being caught at the border. Customs and Border Protection handles initial detention at ports of entry and along the border itself. These facilities are designed for brief stays—technically no more than 72 hours—after which migrants are transferred to ICE custody or, in the case of children, to the Office of Refugee Resettlement. In practice, during the 2019 surge of border crossings, average detention times exceeded a week.

The second path runs through local law enforcement. A provision called Section 287(g), added to immigration law in 1996, allows state and local police to enforce federal immigration law after receiving training from ICE. In practice, this means someone pulled over for a broken taillight might end up in immigration detention if they can't produce proper identification. Civil rights groups have long accused this program of enabling racial profiling.

The third path involves a program called Secure Communities, launched in 2008. When anyone is arrested and booked—for any crime—their fingerprints are checked not just against FBI criminal records but also against Department of Homeland Security immigration databases. If there's a match, ICE can place a "detainer" on that person, requesting that the jail hold them for up to 48 additional hours beyond their scheduled release so ICE can decide whether to take them into custody.

Secure Communities has had a turbulent political life. The Obama administration expanded it dramatically, from 14 jurisdictions under President George W. Bush to over 1,200 by 2011. In 2014, Homeland Security Secretary Jeh Johnson discontinued it. In 2017, President Donald Trump restarted it via executive order.

Mandatory Detention: When There's No Choice

Here's where the system gets complicated—and, critics argue, unjust.

In 1996, President Bill Clinton signed two laws that transformed immigration detention: the Antiterrorism and Effective Death Penalty Act and the Illegal Immigration Reform and Immigrant Responsibility Act. Together, they created what's called mandatory detention for "criminal aliens."

These laws expanded the definitions of crimes that trigger automatic detention. Two categories matter most: "crimes of moral turpitude" and "aggravated felonies." Both terms sound precise but are actually quite elastic. An aggravated felony in immigration law isn't necessarily aggravated or even a felony under criminal law—it's a term of art that has expanded over time to include crimes that might seem surprisingly minor.

The practical impact was immediate. From 1996 to 1998, the immigration detention population nearly doubled, from 8,500 to 16,000. By 2008, it exceeded 30,000.

What makes mandatory detention controversial is that it removes judicial discretion. Someone with a decades-old drug conviction, someone with a non-violent misdemeanor that didn't even result in jail time, someone who poses no evident threat—all can be subjected to mandatory detention with no opportunity for a judge to consider their individual circumstances.

The American Civil Liberties Union has condemned this practice as violating due process while being both inefficient and expensive. After all, detaining someone costs money—and many of those held pose no realistic threat to anyone.

What Happens Inside

Immigration detention facilities are supposed to meet certain standards. They're bound by the same prohibitions against cruel and unusual punishment that govern domestic prisons, rooted in the Eighth Amendment to the Constitution. The United States has also ratified several international agreements that theoretically apply: the International Covenant on Civil and Political Rights, the Convention on the Elimination of All Forms of Racial Discrimination, and the Convention Against Torture.

Theory and practice diverge.

Reports have documented punitive disciplinary actions that may violate these conventions. The ACLU has noted that complaints of physical, sexual, and verbal abuse by facility officials are "not at all uncommon" and that facilities seem to lack systematic processes for recording and responding to detainee complaints.

The most significant difference between immigration detention and criminal incarceration involves legal representation. In criminal cases, the Constitution guarantees you a lawyer if you can't afford one. In immigration proceedings, no such right exists. You can hire an attorney—at your own expense—but if you can't pay, you navigate the system alone.

This matters enormously. Immigration law is notoriously complex. Representing yourself in removal proceedings against trained government attorneys, while detained and potentially unable to gather evidence or contact witnesses, creates obvious disadvantages.

Asylum and the Question of Credible Fear

Buried within the detention system is a profound tension: among those detained are refugees seeking asylum, people fleeing persecution who have every legal right to ask the United States for protection.

Under the Immigration and Nationality Act, someone stopped at the border who is believed to be undocumented or a potential security threat is classified as an "arriving alien" and deemed "inadmissible." But what if that person is fleeing violence? What if returning home means death?

This is where "credible fear" interviews come in. Asylum seekers undergo screening to determine whether they have a credible fear of persecution if returned to their home country. If they pass this initial screening, their cases proceed to fuller review.

In April 2019, Attorney General William Barr ruled that asylum seekers who pass credible fear screenings and are held in detention cannot have a judge grant them bond—meaning they must remain detained throughout their proceedings, which can take months or years. A federal judge blocked this policy before it could take effect, filing an injunction in a class-action lawsuit brought by migrants and their advocates.

The Mechanics of Removal

Deportation—the government prefers the term "removal"—follows a legal process. Undocumented residents are brought before an immigration judge in removal proceedings. The judge either issues a new removal order or reinstates a prior deportation order. These proceedings are conducted by the Executive Office for Immigration Review, which falls under the Department of Justice rather than the Department of Homeland Security.

In 2019, the Trump administration implemented "expedited removal," allowing immigration officials to deport people more quickly with fewer opportunities to challenge the decision. Under the expanded policy, undocumented immigrants could be rapidly deported unless they could prove they had lived in the United States for more than two years. Legal groups sued, but the Supreme Court ultimately approved the fast-tracked deportations.

The second Trump administration, beginning in 2025, dramatically accelerated deportations. Over 400,000 undocumented immigrants have been deported, while an additional 1.6 million have left voluntarily.

The 2019 Border Crisis

To understand why detention capacity matters, consider what happened in the first half of 2019.

The number of migrants arriving at the U.S.-Mexico border surged far beyond anything the system was designed to handle. On March 27, 2019, Customs and Border Protection held 13,400 people in custody. By May and June, between 14,000 and 18,000 people were being held each night.

To put this in perspective, a CBP commissioner stated on a press call: "A high number for us is 4,000. A crisis level is 6,000. 13,000 is unprecedented."

These weren't long-term detention facilities. They were border processing centers designed to hold people for 72 hours before transfer. When the downstream system couldn't absorb the flow, people backed up at the intake point. Facilities designed for brief stays became overcrowded holding pens.

Three Agencies, One System

Understanding immigration detention requires keeping three agencies straight, each with distinct roles.

Customs and Border Protection operates at the border and ports of entry. They're the first point of contact, handling initial apprehension and short-term detention. If you've ever gone through passport control at an airport, you've interacted with CBP.

Immigration and Customs Enforcement takes over for longer-term detention and handles interior enforcement—that is, finding and detaining undocumented immigrants already living in the country. ICE is where people end up after CBP processing, and ICE makes decisions about detention, bond, and removal proceedings.

The Office of Refugee Resettlement handles unaccompanied children and family units differently from adult enforcement. ORR falls under the Department of Health and Human Services rather than Homeland Security, reflecting a different philosophy: that children, at least, should be treated as a welfare concern rather than purely an enforcement matter.

As of 2025, ICE has reorganized into four directorates: Enforcement and Removal Operations, Homeland Security Investigations, the Office of the Principal Legal Advisor, and Management and Administration. The alphabet soup of bureaucracy continues to evolve.

The Larger Questions

Behind the statistics and procedures lie questions that Americans have debated for generations and will continue debating long into the future.

Who gets to come here? What do we owe to people fleeing danger? How do we balance security concerns against humanitarian obligations? When does enforcement become cruelty?

The immigration detention system embodies America's unresolved answers to these questions. It's a system that processes hundreds of thousands of people annually through a vast network of federal facilities, private prisons, and local jails. It holds asylum seekers alongside people with criminal convictions. It operates under legal frameworks that guarantee fewer rights than criminal proceedings while imposing confinement that can feel indistinguishable from prison.

Whatever one's political views, the scale is undeniable. The United States detains more immigrants than any other nation. What we do with that power—how we treat the people caught in this system—says something about who we are.