Operation Wetback, which was carried out in 1954, accomplished this very successfully. Once illegal aliens began to be rounded up by American authorities, large numbers of illegal aliens started to leave the U.S. voluntarily. In fact, of all the illegal aliens that were forced to return to Mexico in 1954, the majority of them went back voluntarily.
That is a great reminder and worth repeating. I believe there was a program for "willing workers" and "willing employers" at the time called the bracero program. yet ILLEGALS still came.
We had leaders of stature in those days, regardless of the many options outlined none will be enforced today. Period.
To be fair to the leaders of today the problem is there are too many hyphenated groups with too much power for the government to do much of anything. There are the likes of the ACLU pukes, activist courts, anti-"profiling" and "hate crime" laws, and most of all, $$$$$$$ for puke politicians.
I'd love to see Dwight Eisenhower reaction to these pipsqueaks.