It’s often said that the Great Wall of China is the only man-made object visible from space. In the year 221 B.C., as the Qin dynasty’s wars of unification came to an end, its people decided that the best way to protect themselves from their enemies was to construct a physical barrier to hinder them from passing; its effectiveness has always been open to debate.

Donald Trump, keen on symbolism as are the current trend of new leaders who skirt the borderlands between totalitarianism and democracy (we don’t yet know whether it’s simply a bad moment in the history of humanity or whether this will continue for decades to come), not only set forth the construction of a big wall that would block illegal immigrants from attempting to enter the United States in his campaign program, but he has also continued to refer to it throughout his administration.

The Great Wall of China didn’t work perfectly, and neither would a physical wall here, as a high percentage of migrants don’t cross the largest border in the world on foot; only the poorest of the poor do that. It’s far more common for people to enter on tourist visas or in other ways that building a wall will not affect.

More than symbolism, what’s vitally important for the Trump administration is to retake control of its borders and of immigration into its country. A physical barrier isn’t what’s needed; incentives are, so that migration starts to fall.

As an example, the healthy state of the Mexican economy has meant that since 2009, migration trends have reversed as more Mexicans leave the U.S. than enter it. The United States government knows this could alter very quickly with any sudden changes in Mexico’s domestic economy, which would then magnify the problems the U.S. faces today with Central Americans.

In this sense, the Trump government isn’t wrong when it says Mexico will pay for the wall and that it is Mexico's duty to prevent the migration to the United States not only of its own nationals but also of other inhabitants of the region.

It’s no coincidence that the Mexican government of President Andrés Manuel López Obrador has doubled the minimum wage on the country’s northern border and set out a series of fiscal incentives in the same region. Although it may seem so at first, this isn’t a measure aimed at maintaining competitiveness or preventing Mexicans from migrating. It’s an economic barrier to make not entering the United States an attractive proposition for Central Americans.

The agreement announced as part of International Migrants Day is the first commitment of investment and cooperation in Central America, in which the United States will set aside $5.8 billion with Mexico also making a significant contribution. The country’s foreign minister, Marcelo Ebrard, vowed to give $500 or $600 million per year to each country. The objective? To incentivize development and economic growth in the hard-hit countries that make up Central America’s Northern Triangle (Honduras, Guatemala and El Salvador).

Under such conditions, the support programs for Central America are undoubtedly implementing a different kind of wall. Physical barriers aren’t put up today without economic walls going up too.