The U.S. Government could ask the Chinese, Israelis and even some old East Germans for help closing the Southern border. The fraking Romans built two walls across what is now Great Britain before 200AD so maybe we could ask The Italians for some help with a wall? It's not like borders haven't been closed before. ^_^

so how many of these previous walls were successful?

i think the southern border wall should be a pair of walls 200 feet high. 200 feet deep to discourage tunneling , make the walls 2 miles apart with sensors to detect tunneling, put a lethal voltage electric fence between the 2 walls. make the surface between the walls impossible to walk on....

with rough rocks, razor wire, motion detectors etc..... add some auto fire guns to kill anyone in the dead zone.....

a few miles from the wall put up a high fence so that anyone who wants to tunnel will have to dig a 5 mile tunnel.

of course then illegals will use boats along the coasts, and just walk across the canadian border......

possibly more practical will be a nationwide secure id system.

photos, retinal scan, fingerprints, DNA sample, along with a ID chip that can be read from a distance.....

anyone wanting to get a job will have to present their papers and put their hand on a iD reader. this would replace credit cards, much more convenient