Today I learned that it's a federal crime to provide shelter to an unauthorized immigrant. And that we actually prosecute people for it.
A husband and wife live in Saipan (in the CNMI). They go to China to visit Wife's family and the like and meet up with a friend, who's got a 10-year old kid. The friend wants the 10 year old to try out studying in an American school, so the husband and wife take the child to Saipan and enroll him in the public elementary school there.
That's okay; the CNMI allows anyone from China to go there for up to 45 days, without a visa or anything. You've just got to have proof of a return flight back. Which the kid does; he arrived on September 26 (near the beginning of the school year, presumably), and has a ticket back to China for a month later. So the kid goes to school, lives with husband and wife, all is fine. Husband and wife identify the kid a Chinese citizen to the school and Border Patrol, etc., and he lives there for a bit and tries out school.
The kid apparently decides he likes it there, since he skips his flight back and stays with the family (and seemingly keeps attending the school) for around 18 months or so, when he finally leaves. At some point thereafter, the wife voluntarily speaks to immigration officials and tells them everything about the kid's travels etc.
At which point they prosecute both husband and wife for "harboring" an illegal alien. And instruct the jury that to "harbor" an illegal alien means "to provide shelter to".
And get convictions of both family members.
I'll forthrightly admit that I didn't realize that we prosecuted situations like this one. And, to be clear, this is not a "Trump thing" -- the prosecution here transpired in 2015.
Now I know.