Thousands of Ecuadorians, Ghanaians, and Thais want to come to the United States to work. Without them, we'll have lower overall productivity, reduced economic value, and fewer delicious, delicious restaurants. And that's just fine with the Obama administration (and the entire GOP presidential field).

Michael Clemens, an economist at the Center for Global Development, reviewed research on emigration from poor countries and found that increasing labor mobility by just a small amount—allowing 5 percent of people in low-income countries to emigrate—would increase global GDP by several trillion dollars a year. That's more than the added value that would result from eliminating all policy barriers to the global flow of goods and capital, as he stressed in a blog post about the paper.

One reason that even just a little more emigration by low-income workers would add so much value is that people would become much more productive if you could pick them up off the globe and set them back down in a different place:

Take a male construction worker in the capital of Ghana. There isn’t much you could do to greatly raise his economic productivity in Ghana; access to better tools or training might make him modestly more productive. But if you let the exact same person emigrate to work at a construction site in any big U.S. city, his economic productivity would rise roughly 700% to 1,000%.

Luckily, we don't need some kind of deity to move people around like chess pieces on the surface of the Earth, because so many people are willing to emigrate of their own accord. In his paper, "Economics and Emigration: Trillion-Dollar Bills on the Sidewalk?"*, Clemens noted the incredible demand for visas through the U.S. Diversity Visa Lottery, which awards emigration slots mainly to people from developing countries. "In fiscal year 2010," he wrote, "this lottery had 13.6 million applications for 50,000 visas—272 applicants per slot."

And even though both labor unions afraid of losing jerbs and Fencers consumed with xenophobia often claim otherwise, gains from open borders don't go to only migrants. Saying so, Clemens said, would be "like saying that the economic gains from the immigration of Google founder Sergei Brin are limited to the increase in living standards experienced by Brin himself and his son."

He added:

Moreover, apart from stars like Brin, lower-skill workers convey a range of economic benefits to non-immigrant workers, including lower their cost of living, raise female labor force participation, and raise the productivity of investments in new business.

Yet we still turn them away in droves. 

Reason's Shikha Dalmia has documented the current administration's fourfold increase in employer raids for illegal immigrants, as well as how pretty much every GOP candidate sees Mexicans as "the new untouchables of American society."

*The paper's title references a lame economics joke. Which is redundant.

Two economists walk down the street and see a $20 bill lying on the sidewalk. The first economist says, “Look at that $20 bill.” The second says, “That can’t really be a $20 bill lying there, because if it were, someone would have picked it up already.” So they walk on, leaving the $20 bill undisturbed.