Demography 101: Flow, Stock, and the Wall

By David North on January 28, 2019

In the first week of Demography 101 one learns that there are two basic sets of population measures, the stock and the net flow.

Stock counts or estimates the total number of individuals within a given area at a given time, as does a census.

Net flows deal with population movements; usually, the formula for a given amount of time is:

(inward migration + births) - (outward migration + deaths) = net flow

Generally, unless the net inward flow is caused by an advancing army, the impact on the general population of the stock of a particular population is more important than the impact of the inward flows, as the flow usually represents a much smaller number than the stock.

Let's think about how a stock of additional population in the millions impacts the infrastructure, the amount of work done, the number of jobs taken from the resident population, consequences to taxpayers, the upset of the economic order, and the like; these results come from the presence throughout the year, day after day, of the population of interest, in this case, illegal aliens These impacts are huge and long-lasting.

On the other hand, the impact of the inward flow of illegals, who are trying not to be noticed, is different: The desert environment is disturbed, extra trash is found there, and money is spent on the Border Patrol in an effort to limit the number of intrusions. And, of course, the new arrivals will add to the stock of illegal aliens already here. For the most part these impacts are transitory; negative, but transitory.

My colleague, Steven Camarota, in an earlier blog, mentioned estimates of 170,000 and 210,000 successful illegal entries a year across the southern border, and suggests that a wall would pay for itself if it prevented or deflected 60,000 entries a year.

Let's simply look at 60,000, or 170,000 or 210,000 and compare those numbers to the generally accepted estimate that there are 11 million or maybe 12 million illegal aliens in the United States at any one time. The first numbers relate to the flows across the southern border; the second to the stock of illegal aliens in the nation, no matter how they arrived.

Let's turn now to the recent offer of President Trump. If he gets the $5.7 billion he wants for a wall, which will perhaps stop or divert a flow of 60,000 aliens a year, he offered the Democrats the temporary (for three years) legalization of approximately one million people in marginal status (DACA and TPS beneficiaries.)

So, to impede or stop what might be 60,000 a year in inward flows, the president offers temporary legal status to a million aliens. That would reduce the inward flow by one alien annually for every 16.6 aliens allowed to remain in the stock. I do not see that as a good deal for the country.

Unfortunately the press recognition of a flow, such as caravans of a thousand or so from Central America, is much more pronounced — and makes a bigger impression on the White House — than the impact of the continuing stock of millions of illegal aliens; hence the current emphasis on a wall, rather than on an integrated policy of seeking to lower the size of the illegal alien population already in this country.

Both the wall and the caravans are symbols and much easier to understand than the concept of a large (and quiet) stock of individuals who are (mostly silently) doing some (often indirect) damage to this country.

President Trump does not have a monopoly on this policy failing; for decades the actual effort to control the size of the stock has almost always morphed into efforts to control the inward flows from the South — let's hire 5,000 more Border Patrol agents! These have been the reactions of the Clinton, Bush II, and Obama administrations as well.

The further trouble of course is that doing something about the inward flows of illegals is to bring pressure on an external population, a high-visibility group without much political influence. On the other hand, to bring the needed pressure on the stock of less-visible illegal residents is much more difficult because they have relatives, countrymen, sympathetic pols, tender-hearted journalists, and, most importantly, employers, on their side and none of those want to change the status quo.

So the focus on the flow is misplaced, recently and dramatically by the wall and the partial shutdown of the government, just as in the past that focus used to be misplaced on a different partial solution, hiring thousands of more Border Patrol agents.

Don't get me wrong: Stout and tall fences and a substantial staff of Border Patrol agents are both very useful. But our leaders and the press should move past the symbolism of the flow and focus instead on the problems caused by the presence of — the stock of — millions of illegal aliens.

Next: the stock and flow of H-1B workers.

Topics: Border Wall