Bryan Caplan of George Mason University posted some comments I sent him along with some questions about a recent blog post of his. His questions are in quotes, my responses follow. First, some background.

It’s important to separate immigration (permanent) from migration (temporary). Much of what we think of as “immigration” is actually migration as many of them return home. Dudley Baines (page 35) summarizes some estimates of return migration from America’s past.

Country/​Region of Origin: Return Rates

Nordics: 20%

English & Welsh: 40%

Portuguese: 30–40%

Austro-Hungarians & Poles: 30–40%

Italians: 40–50%

Gould estimates a 60 percent return rate for Italians – similar to Mexican unauthorized immigrants from 1965–1985.

There were three parts to the Immigration Reform and Control Act of 1986 that all affected both immigration and migration. The first part was the amnesty. The second was employer sanctions through the I‑9 form that was supposed to turn off the jobs magnet. The third was increased border security to keep them out. For the first two questions, I assume the rest of IRCA was passed.

1. How much higher would cumulative Mexican immigration since 1986 have been if the IRCA’s employer sanctions hadn’t been imposed?

Temporary migration would’ve been higher AND more illegal immigrants would have permanently settled in the United States.

IRCA didn’t change the probability of migrating illegally (Figure 6) but it made them more likely to stay once they arrived (Figure 7). Since IRCA decreased the return rate, the population of illegal immigrants grew rapidly as the inflow was steady. IRCA plugged the drain with border enforcement, not employer sanctions.

Eliminating employer sanctions would increase the inflow of illegal immigrants by increasing their wages but not by much (see point 4 here). The I‑9 did not lower illegal immigrant wages enough to dissuade many from coming because the economic chaos in Mexico made the United States even more attractive by comparison. Mexican unlawful migration thus would’ve been even greater without employer sanctions because the benefits to working here would’ve been larger.

Amnesty increased permanent settlement through chain migration. IRCA granted green cards toroughly 2.7 million unauthorized immigrants that then allowed those new green card holders to sponsor family members who were then able to sponsor other family members, and so on. Each green card holder could have sponsored many immigrants. The amnesty of the nearly 2.7 million increased the number of legal Mexican immigrants by millions more (my best guess).

2. How much higher would cumulative Mexican immigration since 1986 have been if the IRCA’s border security boost hadn’t been imposed? (Your comments seem to suggest that it actually would have beenlower, since guest workers wouldn’t have bothered to bring their families).

Temporary Mexican migration would’ve been higher, BUT fewer of them would’ve settled here permanently.

From 1965–1986, migrants moved between the United States and Mexico because it was easy to cross the border illegally. If they returned to Mexico and they couldn’t find work, they could always return to the United States and find a job. That explains most of the 26.7 million entries and 21.8 million subsequent returns of unauthorized Mexican migrants into the United States from 1965 to 1985. I don’t know what the comparable figures are for 1986-present, but if the pre-IRCA regime continued, they would have been even larger .

Border security raised the price of entering the United States. It also raised the price of leaving by blocking the option to return if the Mexican economy tanked. Once many decided to stay after getting passed the increased border security, they decided to send for their families and settle here.

Later policies like the 3/10 year bars and the post‑9/​11 increase in border security combined with the Great Recession caused an even steeper decline in return rates, but IRCA started it (Figure 7).

The longer and increasing terms of residency for unlawful immigrants wouldn’t have happened if the border remained de facto open. Many of the illegal migrants who came after IRCA wouldn’t have brought their families.

3. How much higher would cumulative Mexican immigration since 1986 have been if the IRCA’s hadn’t been passed at all?

More Mexican workers would’ve migrated BUT many fewer of them would have permanently settled here as immigrants. The circular flow of 1965–1986 would have continued and probably increased. Without the amnesty, there would’ve been roughly 2.7 million fewer Mexicans with green cards, which would’ve meant many fewer green cards for Mexicans in the future.

P.S. Do your answers account fordiaspora dynamics?

I do account for diaspora effects. According to Doug Massey’s data (p. 69), the percentage of migrant heads of household with a spouse and/​or children in the United States dropped from 1965 to 1985, loosening their familial ties. Those with immediate family in the United States saw the size of their households increase. From the 1965–1970, the odds of unlawful immigration by men rose until it stabilized in the 1980s before IRCA (p. 69). Those behaviors are not consistent with migrants looking to settle permanently in the United States.

After IRCA, the percentage of undocumented immigrants who were women or nonworkers jumped (p. 134), consistent with permanent settlement rather than temporary migration.

The amnesty portion of IRCA increased the size of the Mexican-American population. The legal immigration system emphasizes family reunification. Amnestied Mexicans were thus able to sponsor their family members after receiving their green cards and even more so after about 45 percent of them earned citizenship. Green cards for Mexicans would’ve increased at a slower rate without IRCA. IRCA’s amnesty increased the size of the Mexican diaspora and set it up to grow more in the nearly 30 years since then than it would have otherwise.

The family-based immigration system that turned the amnesty into such a long-term increase in Mexican immigration was created by the Immigration Act of 1965, which is reviled by restrictionists today. Ironically, the family reunification portion was concocted by restrictionists who lobbied for it. The American Legion and the Daughters of the American Revolution opposed the abandonment of the national origins system under the 1965 Act. According to historian (and noted restrictionist) Vernon M. Briggs Jr., they lobbied for a family-based immigration system because they thought it would preserve the European ethnic and racial balance of immigration.

That backfired.

I have one question for you, Bryan: If the benefits of immigration are as great as we like to argue, why are there so few illegal immigrants?

P.S. I think about Bryan’s brilliant book The Myth of the Rational Voter more than any other I’ve ever read. If you have any interest in economics, politics, or are just perplexed by the silly things politicians say, I highly recommend it.