Tag Archives: quantitative estimation

How far are we from open borders?

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I’m planning to write a multi-post series on how far the world as of now is from open borders. There are many different angles from which the question can be approached. In this post, I will provide a brief summary of the four major angles I’m considering. In future posts, I’ll elaborate on the individual angles. The four angles are:

  • Legal
  • How many want to move
  • How desperate people are to move
  • How different the world would look (economically, socially, etc.) under open borders

The idea behind the post is quite similar to the idea behind my earlier post titled open borders is a radical proposal. They differ both in rhetorical approach and in the particular points of emphasis. The earlier post focused on how open borders is, in many ways, historically unprecedented whereas this post focuses on how it significantly differs from the current status quo. Rhetorically, while the earlier post viewed open borders as the thing being judged in relation to the status quo, this post judges the status quo as a deviation from open borders.

Legal: Presumption and reviewability

Before looking at the status quo, it might be worth thinking about how an open borders regime might look like. Such a regime is not inherently incompatible with passports and visas. For instance, people need driver’s licenses to drive vehicles on roads, and the test is not completely trivial, but it is generally open and not too difficult for somebody who’s willing to work for it and take the test enough times. Democracies may require voter identification in order to allow people to vote, but they are still considered to have universal (adult) franchise if such identification is easy to obtain.

How closely a passport and visa regime comes to open borders would therefore depend on how procedurally straightforward it is to get a visa or equivalent permission to enter another country. In cases where this is just a matter of paying a small fee to have an application processed, we’d be close to open borders. In cases, however, where visas can be rejected for a variety of reasons, we’d need to start looking more closely at the list of reasons why a visa might be denied.

Legal theory has a useful concept called presumption of innocence, also known as innocent until proven guilty. The principle is generally applied in the context of criminal trials: the legal burden of proof rests on the state (the prosecuting party) that is trying to show that the accused is guilty, rather than on the accused to prove his or her innocence. Part of the justification for this asymmetry is the coercive and destructive nature of the punishment that people suffer once they have been found guilty. There is a strong presumption against forcibly making an innocent person suffer such punishment. The extent to which such a presumption exists, and should exist, is a matter of considerable debate, but the idea is straightforward.

In an open borders world, the analogous doctrine would be a presumption in favor of free movement, and the equivalent slogan would be “unrestricted until proven dangerous” — for approximately the same reasons: denying a person who expresses the desire to move to a new country the ability to do so is a significant infringement of the person’s freedom, and as such, deserves justification. There would be two components to this:

  • When denying a visa, a consulate would need to provide a specific reason for doing so and cite evidence in support of the reason. The evidence would need to be made available to the applicant.
  • The applicant would be in a position to challenge the consulate’s decision in front of a relatively neutral arbiter, who would hear out both sides and come to a decision.

Of course, just having the above doesn’t equate to open borders — the criteria may be very transparently stated but still very stringent. The same principle applies in criminal law: criminalization of a large number of victimless crimes, even if the law is executed fairly, can still be an indicator of an unjust and tyrannical society.

How far is the status quo from this open borders-like scenario? Very far. The United States is perhaps a somewhat extreme example, but not by a huge margin.

According to official estimates (linking HTML page), about 15-20% of applications across all nonimmigrant visa categories to the US in 2012 were rejected initially, and only about a third of the rejected applicants were able to overcome the refusal and get a visa eventually, resulting in a rejection rate of 10-15%. The primary reason for rejection is Clause 214(b): failure to establish entitlement to nonimmigrant status. In other words, the consular officer rejected the visa application on the grounds that the applicant might transition to long-term permanent resident status. Thus, not only does the US lack a direct route for most long-term migrants, it also coercively restricts people who want to visit the US for the short term (for work, study, or tourism) on the grounds that they might stay too long (with no evidence needed that such a long stay would hurt anybody). The US also has a doctrine of consular nonreviewability (see here and here): decisions by consular officers cannot be challenged by law or overturned by anybody, even the US President. Combine consular nonreviewability with Section 214(b), and the paradigm we basically have is the migration analogue of guilty until proven innocent.

How many want to move

I looked at this question in some detail in my earlier posts here and here. But here’s a quick summary: according to polling data on migration (the most recent available poll is here) about 13% of the world’s adults, or 630 million people, say that they are interested in permanently moving to another country. This is a huge number. In a world with open borders, there would still be people who are unable to move to another country due to personal issues, but it wouldn’t approach 13% of the world population. It’s safe to say that this is far from open borders. (The potential distinction between stated and revealed preferences is implicitly handled in the next point, which deals with how desperate people are to migrate). About 138 million people expressed a desire to permanently relocate to the United States. For contrast, the total annual number of people who migrate annually to the United States (through authorized and unauthorized channels) is a little over a million.

In his post titled Some Unpleasant Immigration Arithmetic, Bryan Caplan proposes an Open Borders Index as follows:

Open Borders Index = C/F

where C equals the total number of immigrants who enter the country every year, and F equals the total number of people who would annually enter the country under open borders. Caplan argues that C/F would be 0 under perfect closed borders and 1 under perfect open borders, and therefore it provides a normalized measure of border openness. He estimates that the C/F ratio for the United States is about 0.05 (i.e., about 20-30 million people would migrate to the US annually under open borders), and that the United States is thereby far from open borders. While the specifics of Caplan’s estimate can be disputed, the general idea suggests that the United States in particular is quite far from open borders.

How desperate people are to move

Desperation can be measured by the amount of resources people invest, relative to their current financial situation, to migrate. On the side of migration via legal authorized channels, this includes the fees that people pay as visa fees and lawyer fees. On the side of migration via unauthorized channels, this includes coyote fees as well as fees for document fraud that people who enter in an authorized fashion may pay in order to overstay their authorized stay. The cost measures need to be viewed in conjunction with the number of people who are willing to pay these costs. All these measures point in the direction of the world being quite far from open borders. Coyote fees from Mexico to the US are in the $3000-4000 range, and there are estimated to be millions of illegal immigrants from Mexico to the US, many of whom were smuggled via coyotes (others overstayed legally obtained visas). Coyote fees from China to the US have been estimated at $75,000, and although there are fewer Chinese who use coyotes to get into the US, the number is nontrivial. Note that coyote fees are an underestimate of the costs of moving, because migrants moving illegally often need to take other precautions in order to avoid being caught, and often need to tolerate inhumane conditions during the course of their movement – all costs that would need to be factored in. Finally, these fees should be considered in relation to their home country income. For the profile of people that migrate illegally from Mexico to the United States, coyote fees are generally equivalent to about 1-2 years’ worth of their current income.

How different the world would look if we had open borders

Finally, let’s consider the impact on economic output. Again, the estimation exercise is tricky because of the significant deviation we’re making from reality. A literature review by Clemens (2011) cites estimates suggesting that removing barriers to global labor mobility would yield world GDP gains anywhere between 67% and 147.3%. To rephrase, Clemens estimates that the status quo is shrinking world GDP to somewhere between 40% and 60% of what it might be under open borders. In the median case, open borders would “double world GDP” or equivalently, closed borders are “halving world GDP.” In contrast, ending all trade barriers is estimated to raise world GDP by about 5%. This isn’t surprising. Labor is a large share of the economy, and a lot of the world’s labor is confined to relatively unproductive segments of the world economy. Freeing people to move to places where their labor can be used better would lead to more production. How much more is debatable, but an estimate of doubling world production isn’t completely out of the realm of possibility when viewed in conjunction with the very large number of people who want to move. These same estimates also suggest that much of the gain in production – and consumption – would be experienced by the world’s currently poorest people, leading to a significant reduction in, and perhaps an elimination of, world poverty. If we take utility to grow logarithmically with income, then this distributional aspect argues even more strongly in favor of the idea that open borders would increase global utility tremendously. Open borders would also significantly reduce global inequality. For instance, a paper by Branko Milanovic estimates that under the status quo, country of origin accounts for 2/3 of global inequality (controlling as best as possible for other attributes). While the country of origin would still play a significant role in global inequality under open borders, there’s strong reason to believe that the fraction of global inequality accounted for by country of origin would be far lower than it currently is.

The cultural, social, and political effects of open borders are harder to quantify, but their existence is undisputed. To a large extent, the pushback to open borders is precisely because of the huge perceived cultural, social, and political changes that might be unleashed through open borders. Whether these effects are a net positive or a net negative is a more difficult question that the site at large is devoted to, and is beyond the scope of this post. What’s important is that the effects are significant, indicating that the world is far from open borders in a meaningful manner.

A case for open borders that is radically agnostic about migrant count

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In a previous post, I considered the considerable divergence, even among open borders advocates, about the raw count and selectivity of migrants under open borders. I argued that it is important to get more clarity on these questions, including understanding the source of disagreement and how different views regarding these can affect the other estimates (including economic growth estimates) related to open borders.

In this post, I attempt to sketch several arguments that could form building blocks of a case for open borders that is radically agnostic about how many people would move.

The right to migrate argument

This argument states, simply, that people have a right to migrate. Denial of this right is immoral. How many people would end up choosing to exercise that right is not of direct relevance. Migration restrictions are immoral because they prevent a large number of people who are in a position where they may wish to exercise the right from doing so. The human capabilities case for open borders is somewhat similar.

The lower bound argument

This argument states that even the lowest possible estimate of how many people would actually move under open borders (perhaps such estimates can be obtained by looking at the number of people who have moved under relatively modest migration liberalization regimes) is high enough to make open borders worthwhile. Whether we are talking of 10 million people over a decade or 200 million people over 2-3 years, open borders would have huge impact.

The “it anyway won’t happen immediately” argument

This argument views open borders as a goal we should set our sights on as we gradually work towards it. Thus, determining the numbers of people who’d migrate under complete open borders is at best an illuminative theoretical exercise and at worst a distraction from the more important goal of seeking marginal change that is far better understood. Some proponents of this argument many view open borders advocacy as a means for shifting the Overton window in a manner that makes immigration liberalization appear to be a more “moderate” position.

The “market forces will prevent swamping” argument

One of the concerns that critics of open borders have is that under open borders, countries (mostly rich countries) that are attractive targets for immigrants will get swamped with large numbers of migrants. This is part of the motivation behind the desire to estimate how many would move under open borders. Some open borders advocates believe that market forces, loosely defined, will take care of this concern. If too many immigrants are moving into the area, rents and other prices will rise and wages will fall to the level that it is no longer attractive to move to the destination. Other non-pecuniary negative feedback loops may also counter the swamping threat. Many people use phrases like “migration flows tend to be self-regulating” to describe this perceived phenomenon.

The “however much it takes to attain labor market convergence” argument

This argument states that migration will continue until there is (upward) labor market convergence between the sending and receiving countries. Convergence may not be complete, but may stop when the place premium between the two countries is a factor of 1.5 or less (i.e., there is only a ~50% wage gain from migrating). The point here is that we don’t know for sure how many people would need to move in order for this convergence to occur, because of countervailing factors: governments may begin instituting economic reforms once people start leaving en masse, emigrants may return to the country to set up new factories and business connected with other countries, etc. Or, this may not happen. Uncertainty about how things play out result in considerable agnosticism about the number of people who move, but relatively more certainty about the nature and desirability of the eventual outcome for humanity.

A Thought Experiment: Haitian Migration

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As Vipul recently noted, one of the biggest questions surrounding open borders is just how many people would move to a new country. The estimates of doubling world GDP rely on this being a very large number. On the other hand, large numbers of immigrants moving to the first world also increase the concerns surrounding political externalities or the overpopulation and environment effects of migration. The number of immigrants who decide to move can potentially have important consequences for good or ill. At the same time precise estimates of how many people might move are likely to be impossible. We should probably expect at best to come to basic estimates.

But one way to help with that is to receive a multitude of informed opinions on the question and thus I come to you dear readers!

Since examining the entire world at once with this question is likely to be extremely complex, let’s use a particular country as an example: Haiti. Let’s get some basic facts about Haiti down as a way of making this task easier. Haiti’s current population is slightly under 10 million people with about a 1% growth rate under current birth/death/migration rates. The country currently has one of the highest emigration rates in the world at 5.5 people out of every 1000 leaving every year. Current income is also one of the world’s lowest with GDP per capita (purchasing power parity) at about $1,300 a year. This helps contribute to Haiti being one of the countries with the highest wage ratios with the US in a paper written by Michael Clemens meaning the potential economic gain to migrants is among the greatest (see page 11). The United States is home to currently over 500,000 Haitians with most in Florida and New York. According to Gallup polls, about a quarter of the adult Haitian population would like to migrate to the United States in particular. That would be about 1.5 million people (including everyone over the age of 15 as “adults” which depending on Gallup’s definition of adult is likely an overestimate, but then not including any children these migrants may wish to bring).

So my question to readers, if the United States were to open its borders tomorrow how many Haitians do you think would come here? Would everyone expressing an interest come or would economic factors stop them? Would the opening of borders increase how many would want to come? If other developed countries were to open their borders how many Haitians would that draw away from coming to the United States? And how much of a difference would at least partially French-speaking countries like France, Belgium, or Canada opening immigration have on drawing Haitians away from the US? Finally, would there be a difference in the amount of Haitian migration if the US opens its borders generally or if the borders are opened for only Haiti in particular? And would this emigration be a solution for Haiti’s numerous problems?

Migration: how many, what kind, and why it matters

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This post is an introduction to a planned series of posts (some by me, some perhaps by others) that explore questions related to how many people might move under various changes that lead towards open borders (locally or globally). The goal of the current post is to explain why I consider the question extremely important. A subsequent post will take a somewhat opposite stand: namely, try to sketch a case for open borders that is independent of how many people might move. Later posts will look at specific policy changes, some of them realistic and others less so, and estimates of what might happen under these. Another area I plan to explore is the question of what the most critical bottlenecks are to large-scale migration (the most obvious candidates are housing and infrastructure) and what limits they set on migration rates.

A while back, I wrote a blog post critical of what I called “economic determinism”: the idea that migration flows are determined completely by economic conditions and that legal barriers to migration have practically zero effect on the magnitudes of migration flows. There are factors other than economic conditions and legal barriers to consider as well, of course: factors such as cultural connections between the sending and receiving country. Alvaro Vargas Llosa’s recent book Global Crossings: Immigration, Civilization, and America drove this point home for me. So, I guess the position I am broadly critical of could be expanded beyond economic determinism to what I might call “restriction irrelevantism”: the idea that restrictions imposed by nation-state governments on migration are largely irrelevant in terms of their effect on the magnitude and nature of migration flows.

Vargas Llosa is definitely not an economic determinist, but whether or not he’s a restriction irrelevantist remains to be seen. This article seemed to suggest that he might be, but op-eds tend to be oversimplifications, and his book, which I haven’t completed reading, may offer a more nuanced picture. I was nonetheless somewhat disappointed by the fact that Chapter 3 of the book, titled “Why They Move” and otherwise excellent at considering the motivators for migration, gave short shrift to the idea that different degrees of restrictionism in different target countries might significantly affect people’s decision of whether or where to migrate.

In any case, this blog post is not about the somewhat extreme position of restriction irrelevantism, which may or may not have real proponents. The majority of proponents and opponents of open borders do not subscribe to restriction irrelevantism. Rather, I think there’d be general agreement that millions more would move, temporarily or permanently, under open borders. But “millions” is a vague term. It could range from an extra five million people over the next two decades to an extra 100 million migrants (many of them temporary) within 2-3 years of global open borders (the main data for how many would move under open borders in terms of the stated preferences of potential migrants are the polling data on migration, which suggest that over a billion people want to go to other countries temporarily or permanently, and about 500-700 million people think they would make long-term moves if they were allowed to). One could come up with a fairly diverse (albeit less so) range of estimates for the number of people who might move under a more targeted open borders regime. For instance, if the United States announced open borders for Haiti (population about 10 million), one might envision a scenario of anything between 2 million people moving to the United States over the next year to a roughly equal number moving to the United States over the next two decades.

The closer the proposed change is to the status quo, the less likely the range of disagreement, but since we are talking here about relatively radical ideas such as open borders, there could be considerable divergence of opinion.

Closely related to the question of how many is the question of who. Many arguments offered by open borders advocates rely on the crucial idea that migrants self-select, i.e., it is not all that easy to migrate to a new land, and therefore migrants are not representative of the populations they hail from, but rather, are selected for positive qualities. As BK has pointed out in the comments (see for instance here and here) you can’t have your cake and eat it too for selectivity: if your estimate says that 25% of the population from region A will move under open borders, you can’t assume that the average migrant who moves will be selected to be in the top 1% of people from region A.

While the precise economics behind double world GDP estimates tends to be complicated, an important point is that all the estimates of huge economic gains also predict that this happens through large numbers of people moving. If, in fact, large numbers of people do not move, then at any rate these specific estimates are not applicable (there may be other mechanisms by which world GDP might increase considerably, such as innovation, but at any rate the specific estimation exercises of the papers would be flawed if very few people moved). For instance, in his blog post about John Kennan’s paper on Open Borders, Nathan Smith writes:

In predicting the volume of migration, Kennan does not assume that humans are strict homini economici who will go wherever they can earn the most. He writes:

One might initially expect that in a world with open borders, everyone would move to the most productive location. But this ignores the strong attachment to home locations that is evident in the data.

He takes this into account by making the migration decision probabilistic, such that the proportion of people who stay in a country is the same as the proportion of the rich-country wage that is paid in that country. For example, if there are open borders between the US and Puerto Rico, and Puerto Rican wages are 2/3 of those in the US, then 2/3 of Puerto Rican adults would stay in Puerto Rico. This roughly fits the data in that particular case, but there is no theoretical motivation for that particular functional form. Relative to a homo economicus model in which everyone who could earn more elsewhere migrated, this assumption causes Kennan to understate the economic benefits of open borders. On the other hand, it also makes Kennan’s version of open borders less scary than it would be if all who stood to gain economically from migration migrated.

This still posits a large number of people who’d move under open borders. Nathan writes later (emphasis mine):

Now, two big things we would like to know about open borders are (a) how many people would move, and (b) how much would world GDP actually increase. If I’m not mistaken, Kennan could easily derive estimates of these things from his model. But he doesn’t. He doesn’t tell us how world GDP would rise under open borders, in the short or the long run. He doesn’t tell us how many people would move, or where they would come from. I think Kennan’s model implies a short-run increase in world GDP of about 65%, and I’m pretty sure in the long run world GDP would double. Since the increase in the effective labor supply comes from growth in the populations of rich countries where labor productivity is high, I think Kennan’s model implies that rich countries’ populations would more than double due to immigration under open borders.

Another related concern is swamping. One of the main concerns of people ranging from hardcore restrictionists to moderate pro-immigrationers and even some who identify as being pro-open borders is that true open borders would lead to very large numbers of people moving over short time periods in a manner that would strain housing, electricity, water supplies, and other infrastructure in the countries receiving the immigrants. The typical response is to point out that (i) borders can be opened somewhat gradually to minimize the possibility of an immediate flood of people (see here for instance), and (ii) in any case, migration flows will tend to be self-regulating and people are likely to plan ahead at least somewhat before making a big move. Evaluating the legitimacy of swamping as a concern is part of the reason why it’s important to get a handle on how many might move under migration regimes that move the needle considerably towards open borders.

Finally, in addition to the direct relevance of understanding migration counts and selectivity, making correct predictions, or at any rate, refraining from making laughably wrong predictions, can help build one’s credibility as an advocate or analyst of migration regimes in the eyes of others approaching the matter from the outside view.

Open borders is a radical proposal

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After poring through some of the data on the foreign-born proportions in the US during my spare time this past weekend, I came to the conclusion that other than radical open borders advocates and restrictionists, most people don’t really have an idea of just how radical open borders would be. Many pro-immigration people are quick to point to the US’s experience with open borders in the 19th century. But there’s a lot of difference between then and now. On a variety of numerical metrics, the US as it stands today comes fairly close to where it was when borders were most open. This table goes up to 1990, but the 2010 census data puts the total population at 310 million and the foreign-born population at 40 million, so the 1970-1990 trend is geometrically continued in the 1990-2010 period.

  • The foreign-born population as a fraction of the total US population as per the 2010 census is about 13%. This is quite close to the 1910 historical high of about 15%.
  • The foreign-born population in the 1970-2010 period has been roughly doubling every two decades in absolute terms (it went up from about 10 million in 1970 to 20 million in 1990, then again to 40 million in 2010). Compare that to the US’s heyday of open borders: the 19th century. The foreign-born population from 1850 to 1890 grew at a comparable rate: up from 2.2 million in 1850 to 5.6 million in 1870, and then again to 9.2 million in 1890. Note that the Chinese Exclusion Act and related restrictions started kicking in the last quarter of the 19th century. It’s true that the period from 1920 to 1960 saw little growth in the foreign-born population, due to closed borders.

If the foreign-born population in the US continues to grow at roughly the same geometric rate as for the last 40 years, it will be about 55 million in 2020 and about 80 million in 2030. Possibly by 2020 and definitely by 2030, this would mean that the foreign-born share of the population would be well past the 1910 peak.

What would happen under an open borders policy today that mimicked the pre-1875 immigration policy of the United States? I think it’s safe to say that the growth rate will be notably higher than under today’s business as usual scenario. Even people friendly to open borders worry about getting swamped, which is why many propose a gradual opening of the borders. On the upper end of the estimates is David Henderson’s speculation that up to 300 million people could migrate to the United States in the first two years after open borders. But even a moderate view would involve about 10 million people migrating (many of them temporarily) to the United States in the first year following radical open borders. Since the exact smoothing of the flow will depend on the precise policy contours, I’d say that an increase in the foreign-born population of the United States by about 50-100 million in the first decade following open borders (or something close to open borders, such as DRITI) is a fairly conservative, low-end estimate. If you applied the lowest end estimate of this range, 50 million, assuming that the borders opened in 2010, then in 2020, the foreign-born population of the United States would be at about 85-90 million (give or take a few existing foreign-born people dying), which would make the foreign-born proportion in the United States between 20% and 25% — way higher than at any time in US history. If you took the higher end of the (still conservative) estimate of 100 million more foreign-born people in the United States after a decade of open borders starting 2010, that’d be about 135-140 million foreign-born in 2020, out of a total population of somewhere between 400 and 450 million, which would be 30% or more of the population. (Note also that, for comparison, according to polling data on migration, about 135 million people claim they would move to the US in the near future if the US allowed them to do so legally, and this is approximately in line with the above estimates).

[I’m starting 2010 because that’s the last year for which census data is available, though of course one cannot travel back in the past to open the borders].

How does this compare to other countries? Here’s a chart of the foreign-born shares of OECD countries (it’s a few years old, unfortunately). The only countries that have a ~20% or higher population share are Luxembourg, Chile, Australia, New Zealand, and Canada. Luxembourg is extremely small, and is part of the EU, so its anomalously high value may be worth discarding. With the exception of Luxembourg, none of the foreign born shares crosses 25% (though this might have changed since 2006, for which the data was available). Chile’s inclusion in the OECD is misleading for the purposes of this comparison, since its per capita GDP is less than $20,000, so less than half that of the United States. Canada, Australia, and New Zealand have extremely low population densities overall. According to Wikipedia’s summary, the US ranks 76th in population density with a density of 34 people/square kilometer. Canada (4 per square kilometer), Australia (3 per square kilometer), and New Zealand (16 per square kilometer) fail to make it to the top 200 in the list. If you exclude all of these, you’re left with basically no country.

But even if you keep Canada, Australia, and New Zealand in, the most ultra-conservative estimate for the foreign-born share in the United States under an open borders type policy is comparable to the highest foreign-born currently seen in the OECD, and more realistic estimates of what would happen in the US under open borders with respect to the foreign-born population place us literally in uncharted territory.

All these data are of course well known to most people in the migration debate. Restrictionists often embrace statistics and factoids of just the sort described here to paint open borders as truly lunatic. And in a sense, they’re right. Open borders is a truly radical, unprecedented proposal. Historical analogies can get us this far, but they simply don’t cut it quantitatively when describing the potential effects (good or bad) of open borders today.

Note that the reason I focused on the United States is simply because I’ve been looking at US-related data in the recent past. However, the case for open borders is universal, so one might wonder if there are other countries for which open borders would be less unprecedented. I don’t know an answer offhand, but it’s also true that many other countries are much smaller (in area and population) compared to the US, so their enacting open borders wouldn’t quite mean the same thing as the US doing so. However, I don’t see how the stats would look less dramatic for most other countries. If Canada announced open borders, then given that the population of Canada is about 1/10 that of the US, a much smaller migrant inflow would have a much larger impact on the foreign born proportion. In fairness, though, it may be argued that since Canada has a much lower population density, some of the overpopulation-related arguments touted by restrictionists have far less force in Canada.

What I think this points to is that when open borders advocates rely on historical precedent regarding open borders, they need to determine the appropriate adjustment factors for a reasonable comparison between the past and present, and justify what these adjustment factors should be. A naive copy-and-paste of population growth rates between the past and present suggests that the current immigration policy of the United States (and possibly of many other countries) already produces results similar to the heyday of open borders. This also raises the question of why we intuitively expect far larger migration flows today, in both absolute and proportional terms, compared to 19th century open borders. Falling transportation and communication costs are the obvious culprits that come to mind, but other technological and social changes might also be involved (for instance, a society that’s far more welcoming of different races and cultures may reduce the perceived and real costs of migrating for people from these different races and cultures — independent of the role of government policy). The next question would be whether all aspects of society have become faster at equal rates, or whether some aspects (people’s ability to physically migrate) have become much faster compared to others (the ability to form new industries and residential areas to accommodate large population influxes), along with the implications of these different degrees of speeding up for the effects of open borders.