Walls have been used successfully for thousands upon thousands of years. They’ve served many purposes, often multiple purposes at the same time. Some were meant to keep people out, others were meant to keep people in.
The Great Wall of China is a great example of a successful wall that held the Mongols and other nomadic tribes at bay, allowed for the regulation of economic trade, and enabled immigration and emigration controls. The Berlin Wall would be another success, though its goal was not to stop an invasion, but rather to prevent the migration of people fleeing communism in the 20th century as well as to control the entrance of prohibited goods. Countless other major and minor examples exist in history, from Hadrian’s Wall that ran across central Britain, separating the Roman-controlled south from the British tribes in the north to the modern Israeli West Bank barrier wall.
If walls have existed throughout human history, why does the idea of a wall along the southern border of the United States provoke such an emotional backlash for some individuals?
Arguably, it is because a wall says that there is a difference between the peoples on either side of it. A wall has a purpose which ultimately strikes at the heart of our modern, cultural orthodoxies. Its existence is the manifest rejection of the idea that all cultures are equal, that all countries are equal, that all peoples are equal. In the end, a people who build a wall to keep others out are showing the world that they love their people, culture, laws, land, etc. more than those which are foreign to them.