by Gretchen Gavett

It’s the fastest-growing incarceration system in the United States: 3 million immigrants have been held in detention facilities across the country during the past decade.

Each red dot on the map below represents an immigration detention facility and is sized by average number of inmates held daily. Roll over each dot for details; to view changes over time, slide the red triangle or click the play button.

*Only facilities with an average daily population of 1 or more detained immigrants are included. Data for 2011 is through Sept. 9.

Credits: Jacob Fenton, Catherine Rentz, Stokely Baksh and Lisa Hill. Source: ICE.

A detention facility can consist of anything from a massive, privately run center to a few beds in a county jail. They hold illegal immigrants who have been caught coming over the border; asylum seekers; anyone with or without a criminal record who has been found to be in the country illegally by Immigration and Customs Enforcement [ICE]; and sometimes legal permanent residents detained on suspicion of being in the country illegally.

Over the past few years, the detainee population numbers have remained fairly steady, while the number of facilities has decreased by more than 100. The system, essentially, is becoming more centralized.

Since 2005, the budget for immigration detention centers has nearly doubled, now at more than $1.7 billion, according to the ACLU’s Anthony Romero. Mark Fleming, national litigation coordinator for the National Immigrant Justice Center, told us that the federal government pays private detention centers between $80 and $120 per detainee per day, though “costs are in the $30 range.”

In 2009, ICE announced its intent to reform the immigration detention system to “improve medical care, custodial conditions, fiscal prudence and ICE’s critical oversight.” While it plans on opening six new, less penal facilities including this one in New Jersey, the Houston Chronicle reports that internal ICE documents still “paint an often bleak picture of the inside of the nation’s immigration detention system.”

Here are some of the key dates in the evolution of the U.S. immigration detention system:

Early 1980s — Privatization begins

The Immigration and Naturalization Service [INS] signs a contract with the Corrections Corporation of America [CCA], beginning the outsourcing of immigration detention services.

1996 — The Illegal Immigration Reform and Responsibility Act

The new law calls for the mandatory detention of illegal immigrants with criminal convictions, and profoundly alters how much discretion immigration officials could give cases.

Early 2000s — Post-9/11 reorganizations

The government agencies charged with regulating immigration, including the INS, were eliminated in 2003 under the Justice Department. Three new agencies — ICE, U.S. Citizenship and Immigration Services [USCIS] and Customs and Border Protection [CBP] — were formed under the new Department of Homeland Security [DHS]. With this reorganization, the line between criminal and civil enforcement of immigration issues becomes blurred.

The law also leads to a boom in the number of border patrol agents; according to DHS, “since 2004, the number of civilian ‘boots on the ground’ along the Southwest border has increased by nearly 85 percent to more than 17,700 Border Patrol Agents today.” This increased enforcement also increases the number of beds needed across the southwest.

2005 — Bush administration announces end of “catch and release”

Up until this point, illegal immigrants without criminal records were given a summons to attend an immigration hearing and then released back into the community until their hearing date. In 2005, then-DHS Secretary Michael Chertoff announces an end to “catch and release,” saying the agency has begun building up detention bed space to house immigrants until their deportation hearing — a program called “catch and return.” The number of beds has since grown from 18,000 in 2005 to 33,000 in 2011 — an increase of 85 percent.

2007: Push for comprehensive immigration reform fails

The failure of the Bush administration’s reform bill, which would have offered legal status to millions of illegal immigrants, left the focus on enforcement tools like “catch and return” — and left many immigrants detained.

2008: Secure Communities starts under Bush administration

Secure Communities is a program that stems from post-9/11 attempts to increase collaboration between local law enforcement and the FBI to detect national security threats. The same type of technology is now used at ICE to track people with immigration violations: Once someone is arrested, their fingerprints are entered into a national database that checks for both outstanding warrants and immigration violations.

According to insiders, Secure Communities, which has been ramped up by the Obama administration, has become increasingly important to ICE because Congress requires that the agency detain and deport 400,000 illegal immigrants per year — and ICE’s funding depends on meeting that quota. Since 2008, immigration detention facilities have held an average of 30,000 detainees per day. During the Obama administration, more than 1 million people have been deported.