A fence is useless without troops or guards or proper laws, they will just dig under it, go over it or frankly cut a hole in it and the Dems would assist them in doing it. Unless you have the manpower and the right laws, its useless.
Now, troops, shoot on sight orders and severe penalties would help and a good start.
You cross the border illegally, get caught, dna taken,databased, immediate expulsion no questions asked and a 10 year exclusion order.
You come back again, immediate 1 year jail term and then deportation with lifetime ban.
This nannying has to stop. You put the right deterrents, the problem will stop.
Now start fining and punishing the Mexican Govt for every illegal that crosses will soon spur them into action.