>>6666479For a whole host of reasons, anon.
One of the key ones being geography. Mountains, desert (inb4 hurr durr, Great Wall of China), and the fucking Rio Grande extends into northern New Mexico, and is easy as shit to cross so its not as if the wall can just end where it touches the Rio Grande.
The next is that, while our relationship with Mexico has never been great, it has been ever improving, and building a massive wall right on our border with them like they're North Korea would royally piss Mexico off. Suddenly an increasingly friendly nation becomes one of our worst enemies again, where that nation just so happens to be only one of two nations we share a border with.
Then there is the expense, because "the Mexican will pay for it by us decreasing our trade deficit with them" will flat out not magically pay for the expense of just building the wall, much less maintaining and guarding the damn thing
Oh, and on guarding the damn thing, in order for the wall to do its job of reducing overland illegal immigration to basically zero, the wall will have to be tightly guarded by a lot of people with guns authorized to kill anyone who tries to get over or under it. This will inevitably end in reports, pictures, and videos of parents with their children being shot to death by border guards, which will be a massive international embarrassment to the US and will further massively piss off Mexico.
Not to mention that if people can't cross by land, they will cross by sea, meaning the Navy will have to waste its time helping the Coast Guard stop immigration, or the Coast Guard will have to massively expand, further increasing expenses associated with the border wall.
It is simply very poor strategy to build a wall that spans the entire Mexican-US border.
