A new study has revealed that border barriers do, in fact, work.

According to The Washington Free Beacon:

The analysis, by University of Illinois at Chicago economist Benjamin Feigenberg, provides empirical evidence that the construction of border barriers—in this case, the 700 miles of border fencing authorized by Congress in 2006—cuts migration both in the areas where they are constructed and in adjacent territory.

In total, Feigenberg estimates, a fully fenced border would deter some 86,000 people from crossing the border every three months, at a cost of less than $2,000 per person deterred.

These findings provide robust empirical support for the idea of constructing a barrier along America’s often-porous border with Mexico—a proposal long-supported by Republicans, and President Donald Trump in particular, but vociferously opposed by Democrats. The failure to support more border fencing, once a bipartisan goal, may have helped drive the recent wave of immigration that led to a crisis at the border.

To reach his conclusions, Feigenberg examined the results of the 2006 Secure Fence Act, a bipartisan bill signed into law under then-president George W. Bush. The bill called for the construction of some 700 miles of fencing along the Mexican-American border; a subsequent appropriations bill put the exact location of the fencing at the discretion of the secretary of homeland security.

Direct fence construction reduces immigration by 27% while adjacent fence construction reduces immigration by 15%. These numbers are profound and a major affirmation of President Trump’s argument.