Would a wall on the border of Mexico really keep people out? History says no. From the third to the 17th century, China built the Great Wall to keep out nomadic invaders, yet it never prevented any invaders from entering China. Rome had walls on their borders too. That didn't stop the Goths and Vandals from invading. Even as recent as the 20th century, the USSR built the Berlin Wall in Germany to keep people in, yet thousands still managed to escape. So, as history has shown time and time again, border walls are a fallacy and not a functionality.