Well, that's still technically "open". If the border was hermetically sealed (and boats/subs that tried to circumvent it were sunk) that would stop. Pesky international agreements however.
It is true that the United States could treat Mexico the way South Korea treats North Korea. I think that would be a terrible idea for extremely obvious reasons.
You only need to enforce like 1% of the illegal crossings and the 1% facilitating the economy of crossings will be gone.
The US does that! We have border control agents! They regularly apprehend migrants attempting illegal crossings.
True, I should’ve stipulated the right 1%. Those orchestrating the cartel coyotes, etc.
Is this what you meant though?
I'm not following your question-- unless you're confused and think this person is the GP commenter.