I'll start with the verifiable facts:
Texas, which accounts for more than half the border, has almost no fencing, with hundreds of miles of open border at a stretch.
Can it be built? Of course, we built the Panama Canal.
According to the Mexican government from 2007-2014 there have been 164,000 drug related homicides.
There are currently 77 border walls around the world, including France, Sweden, Austria, & Spain - many of them built after 2001.
The discussion: Do nations have the right to protect their borders? If so why not the U.S?