I am not sure if Donald Trump has started to lose his 2020 re-election bid at this point. But I know that the wall will not be a solution to illegal immigration, and it will certainly not make “America Great Again.”

Donald Trump promised to build a wall along the border between the United States and Mexico during his election campaign, “A big, beautiful, tall, and powerful wall.” Everything would be easy and Mexicans would pay for it. Quite to the contrary, two years later, it has been very difficult. Mexicans have not paid for it, and the Democrats in Congress do not want to pay for it either. The wall is not an original idea that Trump had. Many before him have had such an idea; history is full of walls.

They are great physical barriers that demarcate territories and divide populations. They are used as mechanisms for defense and control of land and people. But walls are much more than that; they are ways to make the abstract idea of the border into something concrete. They are symbols of exclusion from others, signs of the division between ‘us’ and ‘them.’ It was like that with the Great Wall of China, built to defend the Middle Kingdom from Mongol tribes, and it was also the case of Hadrian’s Wall, built to defend the Roman Empire from barbarian tribes. But it is not different from modern walls, which are not intended for military defense but rather for political control. The Berlin Wall is the most complete example. It was built by the German Democratic Republic (East Germany) and it was conceived as an “anti-fascist protection wall.” It was said that it was built to protect the socialist state from capitalist conspiracies. And, without saying so, it was used to prevent the escape of East Germans to the west. In short, to keep the “fascists” out and the “communists” inside.

Since 9/11, walls have multiplied. There are more than 50 walls around the world and all of them were built to bar immigrants and refugees. In this new world of walls, many of them are in Europe. And even in the United States, parts of a wall were built by George W. Bush, then construction was suspended by Barack Obama and replaced by more sophisticated surveillance technology. The truth is that walls have never worked well. Not even the Great Wall of China prevented Mongol attacks, nor did Hadrian’s Wall prevent barbarian invasions. Equally, the Berlin Wall, which lasted for 28 years, did not prevent the collapse of communism and the reunification of Germany.

Walls can ease tension and contain violence in times of crisis. They may even buy some time for diplomatic negotiations. But they do not solve political problems. What they truly do is postpone the problems. And sometimes, over time and without resolution, they end up aggravating the problems. But the walls are never a solution. That’s why they fall down, as did the Berlin Wall. And when they don’t fall down, they turn into tourist attractions, such as the Great Wall of China. If walls have not solved problems in the past, why would they solve problems in the present, especially such a serious, difficult and complex one as immigration? A wall does not regulate legal immigration. It may limit, but not stop illegal immigration, especially if war or poverty continues in the home country and the labor situation offers better opportunities for life in the destination country.

Finally, not only do walls not solve problems, they worsen the cooperation that is needed between the country of origin and the host country. Trump knows all that and much more. He knows it because official statistics tell him that the migratory flux to the United States has constantly decreased over the last decade, reaching its lowest level in 2018. He knows that because immigration agencies explain that most illegal immigrants do not jump across into the country. They enter legally with a tourist visa and then remain illegally with an expired visa. He also knows that because the State Department has recently confirmed that there is “no reliable evidence” that terrorists are traveling along the Mexican border.

So why is Trump obsessed with the wall? Because the wall has become a metaphor for his administration. And it is not about the wall itself. It is the controversy surrounding the wall. It is the controversy that serves his ideological and political strategy. The idea of the wall serves first to make visible the separation between ‘us’ and ‘them’ and to nourish his xenophobic and protectionist ideology. And then it serves to polarize American society because a populist strategy survives on polarization.

It is clear that Mexico is not collaborating on the wall, and Congress is opposed to it. And according to the polls, public opinion is increasingly disapproving. I am not sure if Trump has started to lose his 2020 re-election bid at this point. But I know that the wall will not be a solution to illegal immigration and it will certainly not make ‘America Great Again.’