Countries that can't absorb their immigrants are asking for trouble.
Just look at the mess in California.
You need assimilation and the "melting pot" to work - and when you have no control over it, you have the beginnings
of chaos. Open borders are a disaster - and not controlling who can come into your country is ridiculous.
You'll just get a balkanized society like Yugoslavia - with tribal identities and loyalties. You don't end up with "Americans".
Build the wall - control who you let in - how much, how fast, what skills might advance your country, how many
humanitarian cases you can handle, etc. We will certainly be much better off if this is done. The left is out of their minds.
Like Cardboard say, take care of your citizens first, otherwise, why do you need a county?