Does the Border Really Need a Wall or the National Guard?

Donald Trump famously campaigned for President promising a wall along the border (and Mexico was supposed to pay for it). More than a year into his presidency, the wall doesn't yet exist and, of course, it is not necessary. Nor is the National Guard a necessity in place of the wall. Why not? Well, among other reasons, the number of people attempting to cross the border has been steadily dropping for several years now. Look at the chart that was posted by Steve Rattner on the "Morning Joe" show this morning on MSNBC:

Since the beginning of this century the total number of people apprehended trying to cross the border has dropped dramatically. Historically, the apprehensions have been mainly Mexican citizens, and the fall in the overall number of apprehensions is almost entirely due to the drop in Mexicans crossing the border. 

Why has this been happening? Two reasons: (1) demographics; and (2) economics. Here's how my son, Greg Weeks, and I, explained what was happening when we published our book Irresistible Forces back in 2010 (pp. 89-90):

By the beginning of the twenty-first century, the demographic fit that pushed immigration levels in the 1990s was much less in evidence, and there are two complementary reasons for this: (1) declining fertility in Mexico has slowed down the rate of growth of the young adult population; and (2) the previous high rates of immigration of young adults from Mexico to the United States produced a large number of children of immigrants, who have helped to increase the rate of growth of the 15-24 age group in the United States. These trends suggest that the era of demographic fit between the US and Mexico may now be coming to a close, and that future migration is most apt to be a consequence of the longer-term “economic fit” between the two countries—young people in Mexico and elsewhere in Latin America seeking higher paying jobs in the United States that they lack at home. 

However, the end of the demographic fit should also mean that the Mexican labor pool, in particular, will be smaller, thereby increasing the chances that a given individual in Mexico will find employment in Mexico, assuming—and this is no sure assumption—that the Mexican economy does not contract. But this is what the Mexican government had in mind when it created family planning policies, and launched a public relations campaign that aired commercials claiming “the small family lives better.” That logic has been the driving force of fertility decline in many countries, including the United States.

So, we are now seeing clearly the trends that Greg and I thought were in place almost a decade ago. We don't need a wall or the national guard. We just need some social science combined with common sense.