Take a hypothetical country which has a less prosperous country at its border. Many people from the less prosperous country cross the border looking for work and/or to commit crimes (among those crimes, crossing the border illegally).
If it was your country, how would you handle it?
By that reasoning and considering America's relatively high unemployment that has lead to an overabundance of available workers, one would think that immigration would have ground to a halt. Fewer jobs = less incentive to move. That hasn't happened so there is obviously more to this one situation between America and it's southern border.
Actually, illegal immigration from Mexico to the U.S. has ground to "net zero," as this article explains.
I agree with just about everything else you wrote in terms of explaining why the U.S.-Mexico immigration issue has no quick-and-easy solution, as well as why it may even take annexing Mexico to straighten out some of the problems (cartels, corrupt officialdom).
In the meantime?
Coming from Luxembourg:
This is my country and it's called Schengen Agreement
If that country was also inundated with corruption throughout the government and legal system, I would annex the country if it were possible to do this without making the situation worse.
I see this as a distinct possibility. A war of that sort might be, in the long run, of more benefit to the richer country than a war far away.
Of course, if the richer country is of a different racial makeup, some people will try to make it all about race.
It would be a very bumpy road.
I think we should create a program to help "illegal immigrants" achieve full citizenship in whichever country they wish to live - presumably the one they were trying to live and work in "illegally". We are all humans and we all live here, on this planet. I think that each person should have the right to live wherever it is on this planet they wish to live. We need to stop treating each other as intruders in our own world.
Could you explain how that might work without resulting in any number of impossible situations? For example, with high unemployment in the U.S., how would a flood of uneducated and hungry mouths to feed be handled? Why would U.S. citizens accept that?
At least some of the "high unemployment in the U.S." is directly related to the fact that there are some jobs that Americans have decided they are too "good" to do, and would rather draw unemployment compensation than do them.
Which in my opinion, is a failure of our culture.