Treat the southern USA border the same way as Mexico takes care of theirs and there will be far less illegals coming.
On the other hand, walls, fences and people with guns enforcing borders will go a long way to stopping illegal crossing.
Like any other crime, of course you will never stop it all.
You can reduce it greatly though.
Yep. You CAN reduce it greatly. Right now the costs of control are way below the cost of leaving the border unsecured. Way below - and Americans know it. We’re not xenophobic, we want our joint property protected. Presidente Arbusto wouldn’t let squatters onto his land, why the hell should we? Hell, I’ve been to Mexico and speak Spanish, so I know why a Mexican would want to come here. I don’t blame them for wanting a better life. That said, it’s not in our best long-term interests to let them come. Particularly when they don’t assimilate.