The construction of a wall on the border between the United States and Mexico, despite the resistance of Congress, will still begin: Donald Trump does not deviate from his election promise to voters in this way to reduce the number of illegal migrants from Central American countries. Money for the construction of a section about 91 km long and almost 5.5 m high - $1 billion - was allocated by the Pentagon. But the effect may be the opposite, believe American demographers Dudley Poston and Peter Morrison, authors of the study The demography of Trump's wall, the translation of which was published in the HSE journal Demographic Review.

The construction of a wall with a total length of 1,162 km was estimated at approximately $18 billion in 2017. Trump promised his supporters that Mexico would pay for the wall, but in the end the president asked congressmen for $5.7 billion for the construction of the wall. After the Democrats refused to approve the allocation of funds, the president introduced a state of emergency - this made it possible to finance the project from the Pentagon budget. True, the military department justifies the construction of the wall by the need to block drug smuggling channels.

The construction of the wall is unlikely to help reduce the flow of illegal migration, Poston and Morrison believe, and may, on the contrary, stimulate an increase in the number of illegal immigrants in the United States. As of 2015, there were about 44 million people from other countries living in the United States, of which about 33 million were legal migrants. Another 11.1 million—about a quarter of all migrants—are illegal (“undocumented” migrants), which is exactly what Trump has in mind. But nearly 4.5 million of these illegal immigrants are people with expired visas who entered the United States legally but stayed longer than allowed. An electronic system for recording entry and exit could have reduced the number of such illegal immigrants, but it was never created, scientists note. The remaining 6–7 million illegal immigrants in the United States are classified as “uncontrolled entrants,” i.e., those who entered the United States without inspection or with false documents, mainly across the border with Mexico (at the same time, according to Pew Research Center estimates, the flow of Mexicans themselves in recent has been shrinking for years), but Trump’s wall will not be an obstacle for them either. The majority are seasonal workers who then went back. Increasing border control (spending on border reinforcement and security rose from $263 million in 1990 to $3.8 billion in 2015) increased the costs of illegal border crossings, causing illegal immigrants to stay in the United States longer, resulting in the number of undocumented migrants in the United States grew from 3.3 million in 1990 to 11.1 million in 2014. The militarization of the border, the authors write, has led to an increase, not a decrease, in the number of such migrants—and Trump’s wall may only accelerate this trend.

Will a wall help stop migrants?