About 80% of new United States immigration court cases (which are Article I courts with only indirect appellate resort to the ordinary judicial branch courts) are to Mexico, El Salvador, Honduras, Guatemala, and China.
As of 2010, when there were an estimated 10,790,000 undocumented immigrants in the United States according to the Department of Homeland Security, the most common countries of origin were Mexico (6,640,000), El Salvador (620,000), Guatemala (520,000), and Honduras (330,000). These four countries account for a little more than 75% of the total. But, China was only the tenth most common country of origins with 130,000. (In between were the Philippines, India, Ecuador, Brazil and Korea.) All of the countries outside the top ten combined accounted for another 1,550,000. So, the current statistics suggest that undocumented Chinese immigrants are particularly likely to end up in immigration court relative to their numbers.
About 34% of undocumented immigrants in the United States have lived in the U.S. for at least two decades, about 61% of undocumented immigrants have been living in the United States for at least a decade, and 91% have lived in the United States for at least five years.
Net undocumented immigration from Mexico is currently zero and has been zero or a net outflow for several years.