In the Rational Middle episode “The Wall”, the experts we interviewed discuss the idea of a border fence — what it does and doesn’t do and why the idea remains so appealing. It also notes that in some areas, a wall already exists. That’s a reference to the Secure Fence Act, which was passed by Congress with bipartisan support and signed by President George W. Bush in 2006. The Economist recently examined the effects of that $2.3 billion project:
So what effect did the first 550 miles have? Not much, suggests an analysis by economists at Dartmouth and Stanford Universities. Arrests at the southern border dropped after the fence was built, but this cannot be attributed completely to the wall, since those years also saw a deep recession. Still, by using a confidential data source—the id cards issued by the Mexican government, through its consulate, to its citizens living as immigrants in America, many of them illegally—the economists have isolated the effect of the new fencing on migration flows. And they calculate that it reduced the number of Mexican citizens living in America by only 0.6%.
By contrast, President Trump has proposed a fence that would stretch 2,000 miles and cost as much as $25 billion by some estimates. The economic analysis of the earlier sections of fencing raises significant questions about what Americans would be getting for their money.