Walls work, if the entity building them want the walls to work:
Funny, and all our politicians keep telling me that a "combination of drones, passive sensors and more Border Patrol agents" will work better. But we don't have enough of those, and no funding for them either. But somehow we still get MILLIONS of illegals across out southern border every year.
Of course, I am a racist in that I don't want brown people to come in illegally and take the prosperity we have, and don't want the poverty that they bring from the shithole country they left.