The Great Wall of Trump may never stand on America’s southern border. Of course, it also seems unlikely that the border would ever be left completely open, with just a bunch of turnstyles to give a general population count.
But it’s an interesting hypothetical that often gets bandied about during immigration debates. Anti-immigration activists argue that if we really opened up our borders, we’d be swamped by the teeming masses. Seems a reasonable speculation, at least superficially. America is very rich with an average per capita GDP of $60,000 (on a purchasing power parity basis). That’s four times higher than the global average.
We have no way to know for sure how many people around the world would move to the United States if our legal barriers were erased tomorrow, but we do know how many say they would like to come — if they had the means and the opportunity. For more than a decade, Gallup has polled adults in countries around the world to see how many would move permanently to another country if they had the chance. About one in five potential migrants — or about 147 million adults worldwide — name the US as their desired future residence. (For reference, net migration to the US has averaged about 1 million per year this decade. Moreover, there are plenty of other advanced economies where the inflow of immigrants as a share of the population is higher than the United States, and whose stock of immigrants as a share of the population is higher as well.) The United States is the top country of choice for potential migrants — far ahead of the next choice, Germany, which is preferred by 39 million potential migrants.
But surely far fewer than 147 million would actually show up even with open borders. Legal barriers are not the only barriers to migration. Consider residents of Puerto Rico, who can freely move to the mainland United States because they are US citizens. As economist George Borjas points out in “We Wanted Workers,” the average construction worker in his thirties earns $23,000 a year in Puerto Rico vs. $43,000 in the continental United States. Moving from Puerto Rico to the continental United States increases lifetime earnings by a quarter of a million dollars, while the actual cost of moving is a tenth or less than that. More than 3 million people live in Puerto Rico, but fewer than 84,000 migrated to the continental US in 2014. This is especially surprising because a Pew Research Center survey over the same time period found that 89 percent of Puerto Ricans “were dissatisfied with the way things were going on the island.”
Or consider an example given by The Economist in July 2017: migration within the European Union. A tad more than 1 percent of Greeks have moved to Germany since the 2010 Greek economic crisis, even though wages in Germany are twice as high as in Greece. Because both countries are within the European Union, barriers to migration are minimal. But the low migration rate suggests that the psychological and social costs of moving are potent and large.
Even migration between two culturally similar areas, like Cold-War era West and East Germany, can be lower than expected. Before the construction of the Berlin Wall, the East German economy was weak and its government undemocratic, yet only 15 percent of East Germans made the trek to West Germany when all they had to do was take a train from East Berlin to West Berlin.
Though many people around the world dream of coming to the United States for a better life, not every dreamer would make the trip, even if they could do it legally. Proponents of open borders often tout the enormous economic benefits of open borders, arguing it could double world GDP or add 78 trillion dollars to the global economy by re-allocating workers to where they are most productive. But things may be a bit more complicated than that calculation suggests. This from economist Adam Ozimek:
The big, fundamental meta question to me is: why is the US richer than the countries that most immigrants are coming from? It’s a combination of different levels of physical capital, human capital, technology, social capital, and institutions. But the last two are extremely vague, and our knowledge of how institutions and social capital emerge and evolve is not great. A decent amount of immigration only changes these things slowly, but open borders could change them very quickly.
Would these changes be positive or negative? We don’t know, but given that the US as already very rich compared to the rest of the world the risks are to the downside. That said, if we could do better at directing immigration to parts of the US I think in some places the risks of massively increasing immigration flows are outweighed by the benefits. Detroit, for example, is not doing nearly as well as the US overall. Ranked as a country by itself, one would not describe it as doing so well that the risks are mostly to the downside.
Fears of the US being overrun with immigrants should we liberalize our immigration laws seem overstated, but the long-term economic benefits of doing might be less than promised as well.
