What's all the hoopla over building a fence or wall at the Southern Border? You can go around it, over it, dig tunnels...or go through Canada.
A fence will not stop illegals, nor will a wall.
Of course a fence will stop 95% if the illegals.
Land mines on fields on our side of the fence will stop a further high percentage.
Arresting and fining any and all who provide the least bit of assistance to Invaders will reduce cut the Invading force by a percentage.
Arresting and fining all who hire illegals will disincentivize the Invaders and thereby significantly reduce the number of Invaders.
Making the act of Invading a felony will reduce the number of invaders by a fraction.
Arresting and fining those who provide housing to Invaders will reduce the number of Invaders by a fraction.
Multiply all those fractional reductions together and you're looking at a nearly complete barrier to invasion.
100%? Not necessary and unrealistic. 99%? Not difficult at all.
And then the US should also start drilling our own oil and cease buying Mexican oil until Mexico starts respecting our national border.
Not to mention the fact that if a fence wasn't effective, all the traitors promoting the Invasion would be supportive of the wasted effort. OF COURSE fences and walls are effective. That's why cities for thousands of years had walls around them.