How long are illegal immigrants held in American immigration prisons?

After being held for up to six months, the US Immigration Bureau detained illegal immigrants and prepared for repatriation. For immigration, the sooner the repatriation, the better. The detainees in this province occupied a prison location (the original prison was overcrowded), which consumed the detention cost. Every prisoner held in the United States costs about $30,000 to $40,000 a year, including eating and drinking, hiring police to look after prisoners, and building tight prisons. However, two things need to be solved before repatriation: handling the necessary identity. Confirm that the prisoner is a citizen of a country that is willing to accept him. Some stowaways who cross the wall and sneak into the United States just don't have a passport (for example, tearing up their passports), and if there is no such person in the country of nationality recognized by prisoners, this person will become a "stateless person", and it will take a long time to finally confirm his nationality, but most of them will be repatriated from the United States in a week or so; Another thing that needs to be confirmed is whether this person has a lawsuit pending. Many imprisoned prisoners or their family members will lodge complaints, such as submitting a "request to suspend deportation" on the grounds of various family difficulties or diseases, or the person has a criminal case in the United States, and all the lawsuits can be concluded before deportation, which requires a long period of detention, even several years, before deportation.