open borders

What the Overstay Rate Tells Us about Border Security

There are two ways to become an illegal immigrant in the United States.  The first is to enter illegally, usually across the Southwest border.  Those folks are sometimes called EWIs, short for entered without inspection.  The second way to become an illegal immigrant is to enter legally and then lose legal status, often by overstaying a temporary visa.  

The majority of new illegal immigrants were EWIs until recently.  A recent paper by Robert Warren and Donald Kerwin at the Center for Migration Studies found that overstays accounted for 58 percent of new illegal immigrants in 2012, a rapid increase over the course of a decade (Chart 1).

Chart 1

Overstays as a Percent of all Illegal Entries


Source: Warren and Kerwin.


At an immigration hearing last week, several witnesses emphasized that continued illegal immigrant entries along the Southwest border and a rising percentage of overstays mean that America’s immigration system is insecure.  In contrast, the higher overstay rate is evidence of fewer illegal immigrants crossing the border as EWIs. 

In calculating the percent of new illegal immigrants who are overstays, the number of EWIs is in the denominator added to the number of overstays.  The number of overstays is the numerator.  The falling number of illegal immigrants crossing the Southwest border without inspection shrinks the denominator on its own, thus boosting the overstay rate.  The surge in the overstay rate is not a lack of security at points of entry and exit but caused by a yuuuuge fall in illegal immigrants crossing the border. 

As evidence for that, I kept Warren and Kerwin’s estimates of the overstay population unchanged but held constant at 2000 levels the number of illegal immigrants entering without inspection.  In other words, I didn’t change the flows in the overstay population but just froze the number of illegal immigrants entering without inspection at the higher 2000 number.  Doing that lowers the 2012 overstay rate to 24 percent – less than half of the rate it actually was and lower than at any point during the entire 30 year period in their paper.

Warren and Kerwin admit that their overstay rate results are sensitive to their estimates of EWIs and how many overstays actually stay long enough to become illegal immigrants.  Small changes in those numbers can shift their findings dramatically.  However, the relationship between the number of CBP apprehensions and the overstay rate supports my simple point (Chart 2).  As the number of apprehensions fell because fewer immigrants attempted to enter the United States, overstays provided a greater percentage of new illegal immigrants.

A Poor Defense of Bernie Sanders

I am not surprised that Bernie Sanders is opposed to open borders.  There is a long tradition of socialists, labor unions, and Marxists opposing open borders in the United States.  Many left-wing intellectuals oppose liberalized immigration, let alone open borders, because it will destroy political support for redistribution and state control of the economy – and they might be right

However, I was surprised by the poor arguments made by Richard Eskrow in defense of Sanders.  On how immigrants affect Americans, there is little difference between the expressed opinions of Senator Sanders and Senator Sessions (see here for a rebuttal I wrote to Senator Sessions, some of the following is borrowed from it).  Senator Sanders, at least, wants to legalize the unauthorized immigrants who are here and probably doesn’t want to seriously limit future immigration.

Below I will block quote Eskrow’s arguments and respond to each one.

“Like many libertarian ideas, ‘open borders’ is bold, has superficial intellectual appeal – and is incapable of withstanding thoughtful scrutiny. It would benefit the wealthy few at the expense of the many, here and abroad.”

One of the main criticisms of immigration by restrictionists is that poor immigrants gain far more than Americans do.  Harvard professor George Borjas’ famous paper on the wage effects of immigration found that Americans benefitted very slightly from it while almost all of the gains go toward the immigrants themselves.  Even excluding the economic benefits to the immigrants themselves, poor Americans just aren’t hurt by having more people here.  Borjas did find that immigrants decrease the wages of lower skilled Americans relative to higher skilled American, but his work is the most negative in the economics literature and should be taken with several big grains of salt.  In that paper, he holds the supply of capital as fixed – an assumption that may be fine for an academic publication but it is not useful for making an argument against immigration in the real world.  The stock of capital is dynamic and increases with the populationIgnoring that important effect would make any increase in population decrease wages.  It should further be noted that Borjas, like other economists, admits that immigration does help Americans more than it harms them, but with some distributional consequences.

National Sovereignty and Free Immigration Are Compatible

A common argument against returning to the immigration policy of 1790-1875, where virtually anybody in the world could immigrate to the United States, is that such a policy would diminish America’s national sovereignty.  By not exercising “control” over borders through actively blocking immigrants, as the argument goes, the United States government would surrender a supposedly vital component of its national sovereignty.  But that argument is mistaken as there is no inherent conflict between free immigration and national sovereignty.

The standard Weberian definition of a government is an institution that has a monopoly (or near monopoly) on the legitimate use of violence within a certain geographical area.  The way it achieves this monopoly is by keeping out other competing sovereigns (aka nations) that would be that monopoly of legitimate coercion.  The two main ways our government does that is by keeping the militaries of other nations out of the United States and by stopping insurgents or potential insurgents from seizing power through violence and supplanting the U.S. government. 

U.S. immigration laws are not primarily designed or intended to keep out foreign armies, spies, or insurgents.  The main effect of our immigration laws is to keep out willing foreign workers from selling their labor to willing American purchasers.  Such economic controls do not aid in the maintenance of national sovereignty and relaxing or removing them would not infringe upon the government’s national sovereignty any more than a policy of unilateral free trade would.  If the United States would return to its 1790-1875 immigration policy, foreign militaries crossing U.S. borders would be countered by the U.S. military.  Allowing the free flow of non-violent and healthy foreign nationals does nothing to diminish the U.S. government’s legitimate monopoly of force. 

Post-World War II Migration and Lessons for Studying Liberalized Immigration



This post is about two issues that are closely related.  The first are some facts and history that help explain why internal migration in post-World War II America was an important component of that economic expansion and likely to be as important in future growth.  Some of this data has applications for future research into the role migration plays as a stimulus to and reaction of economic growth.  The second is how studying this period of American migration could inform the academic literature on the probable effects of removing all or most of America’s immigration restrictions – an admittedly radical policy but one that should be understood.

The facts and history surrounding the post-World War II boom are somewhat controversial.  Some critics of immigration argue that post World War II economic growth occurred with relatively little immigration so therefore immigration is unnecessary for economic growth today.  Those critics are mistaken for many reasons, but fundamentally they misunderstand the role that national migration played in feeding economic growth during the 1950s and 1960s.  Ironically, economic growth at the 1950s and 1960s rate would be exceedingly difficult or impossible to achieve without immigration.    

The economic growth of the 1950s and 1960s with relatively closed borders can likely not be repeated today because there are fewer underutilized Southerners, Puerto Ricans, and women who could enter the workforce as substitutes for immigrants.  Growth during that time was partly fueled by the great migrations (migration is internal movement, immigration is international movement) of Americans from much poorer parts of the country, namely the South and Puerto Rico, to wealthier locations.  After the government began to severely restrict low-skilled immigration in 1921, migrants from the South and Puerto Rico moved in larger numbers to fill the economic gap left by the curtailment of low-skilled immigration, some migrants moved from rural areas to urban ones, and women began to enter the workforce in greater numbers.  Without the great migrations that brought tens of millions of black southerners, white southerners, and smaller numbers of Puerto Ricans to Northern and Western cities, American economic growth during those boom years would probably have been much smaller. 

Furthermore, American internal migration during the 1950s and 1960s was a one-time event due to unique historical, demographic, and economic circumstances that would not repeat today if immigration were similarly restricted.  Migrants and immigrants together as a percentage of the U.S. population move similarly with the average annual hours worked per worker and, thus, the labor component of production.  Lawful immigration is essential to recapturing the labor force growth necessary for approaching the economic growth rates of the 1950s and 1960s.         

The Great Migration

The growth of the post-war American labor force was dramatic.  From 1948 to 1982, the size of the U.S. labor force grew from 60 million to 111 million.  Over the same time, the number of people employed in the U.S. labor market increased from 58 million to 99 million.  The Labor Force Participation Rate (LFPR) increased from 58.6 percent to 64.1 percent and the total number of hours worked per worker decreased by 9.3 percent from 898 hours a year to 814 hours a year – likely because wealthier American workers opted to “purchase” more leisure time – meaning that they can afford not to work so many hours.  Here are the history and economics behind the post-World War II great migrations organized by group.

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