Ugg, the neverending "wall" issue.
I'm personally radically pro-immigration (if we could accept over 1% population increase basically every year via Ellis Island in the 1910's and 1920's, there's literally no reason we cannot do so now, yet I think there is something like fewer than a third of 1% legally admitted each year, now).
But set that completely aside since illegal immigration is different in some key ways. For the sake of argument, let's say everyone agrees that illegal immigration is something we want to limit or obstruct.
The wall is a poor idea to achieve that. It wastes lots of money and has very little effect.
Among the reasons the wall is simply not effective:
1. The majority of immigrants who are "illegal" come legally and overstay. If you are going to spend large sums of money to combat illegal immigration, a physical barrier is simply not an important part of the puzzle.
2. There are plenty of ways to bypass a wall for those who do physically enter illegally. All you are doing, by imposing a barrier, is diverting the routes and means that will be taken to enter. People will take boats, arriving in our
even longer shorelines. Or they will tunnel under, as they already do in places. Or they will go to Canada and come in, as they also do already.
3. The wall is far too long and would require far too many guards to prevent actual incursion. I've read folks talk about how the walls in Israel are quite effective in keeping out terrorists from Gaza. Very true, but that wall is several orders of magnitude shorter. They can spend a LOT more money and manpower per foot of wall and get a far more effective barrier for a much cheaper price in absolute terms. Because it's not very long. They have a tiny border. An actually complete wall between all of the US and Mexico would be easily breached in the places we can't permanently man.
In short, I can't believe the amount of money spent on the wall can possibly reduce the amount of entry to make it cost effective. It's a bad plan.
If you oppose illegal immigration, you should oppose the wall.
If you don't oppose illegal immigration, you should oppose the wall.
And yet, it's a thing.