Although fences are nice, the first rule of border security is to have armed men posted. Fences, walls, moats, minefields, and high tech surveillance are all useless without men on the ground. Wouldn’t take much more than two or three brigades of the regular Army, but that would be too sensible for DC!
Doesn’t even take that. If our immigration laws were enforced all across the country they would stop coming. If they were turned in and deported every time they came in contact with anyone in government from the smallest town all the way up to Feds we would not have an illegal alien problem.