Here it is a SERIOUS problem........
And any successful solution requires SERIOUS thought as opposed to hystrionics. I have yet to hear a proposal which is do-able.
I would prefer something along the lines of citizen/militia type patrols under VERY capable leadership with immediate repatriation. This requires cooperation with the Mexican authorities.
It is the history of the world that the dominant powers attract people from the edges of that power. This goes for nations as well as cities and is, in fact, part of the process of generating and sustaining that power.