Former White House national security official and Hillsdale College lecturer Michael Anton wrote an op-ed recently in the Washington Post where he used falsified quotes, poor legal reasoning, and displayed ignorance of the history and debates surrounding the 14^th amendment to argue that President Trump should unilaterally end birthright citizenship (here’s Anton’s poor response to the devastating criticisms).

Few commentators discussed what the actual effects of removing birthright citizenship would be and instead focused on the comparatively unimportant legal questions. As an exception, my piece for the American Conservative argued that such a move would diminish immigrant assimilation in the United States. However, I neglected to mention any of the social science that backed up my assertion in the American Conservative. Below is a short summary of the relevant literature of the evidence that birthright citizenship helps immigrant assimilation.

There are more assertions that birthright citizenship helps immigrant assimilation and integration than there are individual research papers testing the claim. The major measures of assimilation or integration, both internationally and domestically, consider citizenship important. The National Academies of Sciences (NAS) mammoth literature survey on the integration and assimilation of immigrants in the United States mentions birthright citizenship but never cites research backing up assimilations claims. “Birthright citizenship is one of the most powerful mechanisms of formal political and civic inclusion in the United States,” the report says without any supporting evidence. Later, the authors state, “Birthright citizenship is one of the most powerful mechanisms of formal political and civic inclusion in the United States; without it, the citizenship status of 37.1 million second-generation Americans living in the country (about 12% of the country’s population), and perhaps many millions more in the third and higher generations, would be up for debate.” Again, the report does not provide any support for how powerful a mechanism for assimilation birthright citizenship is except to show that many people born here would not be citizens.

Perhaps the NAS report doesn’t report on how citizenship affects assimilation and integration because the United States has had birthright citizenship for a long time. Because of that continuity of policy, there is no experiment to run in the United States to test the importance of birthright citizenship for assimilation. However, there are three suggestive pieces or strands of literature in the American context. The first is Immigrants Raising Citizens where the author, Hirokazu Yoshikawa, writes that citizenship confers enormous benefits on the children of immigrants but the non-citizen status of their parents limits their ability to help them succeed.

The second piece is the academic literature (see ft. 9) that shows that earning legal immigration status through an amnesty or DACA, even if it results in a status less than citizenship, confers enormous assimilative and economic benefits on the beneficiaries. DACA and amnesties are better experiments to test the importance of citizenship or legal status by itself rather than normal naturalization because studies of the former policies remove the endogeneity concern while studies of the latter variety are plagued by it. That’s a concern because people who choose to naturalize are probably different than those choosing not to, and those differences probably explain assimilative or economic outcomes better than the actual grant of citizenship.

The third piece, a book chapter by Irene Bloemraad, has a section based on interviews with many U.S.-born children of immigrants and what they think it means to be an American. A common answer is that being born in the United States makes them an American. One respondent said “we are all 100 percent Americans, we were born here. No matter what people say, we are Americans.” Another telling exchange went like this:

One Vietnamese American teen’s response was typical. Asked why he thinks of himself as America, he seemed a bit puzzled and said, “Because I was born here.” This sort of response – repeated among a fair number of the teens – did not involve discussion of civic principles of cultural habits. U.S. birth was enough or this teen to feel like he was American.

The third sentence of that quote may worry some folks concerned about the assimilation of the children of immigrants, but I doubt almost any other American-born teen would have answered differently. Compared to Real Americans and not to the Imagined Americans of nationalist lore, birthright citizenship appeared to have helped here.

However, the United States is not a great place to study the effects of birthright citizenship because we have not had a shift or reinterpretation in those rules in over a century. Some countries like Ireland, the Dominican Republic, and Germany, have recently changed their citizenship laws to restrict birthright citizenship, also known as jus soli, and provide a quasi-natural experiment to study these effects

Germany provides the best opportunity to study the effects of birthright citizenship on assimilation. The German Citizenship and Nationality Law of 1913 only granted citizenship to those who had at least one parent who was a German citizen at the time of the child’s birth. In 1999, the German parliament amended that law to create a birthright citizenship component for children born on January 1, 2000, or after if at least one parent had been ordinarily resident in the country for at least eight years. The law also created a transition period for many children born from 1990 through 2000 to naturalize if they met the requirements of the new law.

This change in German citizenship law prompted a flood of research on how the new law affected immigrant assimilation in Germany. Economists Ciro Avitabile, Irma Clots-Figuera, and Paolo Masella looked at how the new German law affected parental integration in a peer-reviewed paper published in the prestigious Journal of Law and Economics. Their paper used responses from the German Social Economic Panel Survey to see how immigrants whose children were affected by the new citizenship law changed their behavior relative to those unaffected by the change in the law. It focused on measurements of interactions with Germans (visiting or being visited by a German in a social situation), speaking German, and reading German newspapers. On all three metrics, the immigrant parents of children who could naturalize became more integrated.

The effects were small but noticeable. The percentage of immigrant parents who had interactions with Germans rose from 71 percent prior to the reform to 77 percent afterwards, spoken German ability rose from 65 percent prior to the reform to 69 percent afterwards, and reading of German newspapers increased from 2.6 to 2.9 on a five-point scale (1 is home country papers only and 5 is German papers only). Importantly, the measure of speaking German doesn’t control for fluency. They also found that the outcomes are larger for immigrants who came from a country that speaks an Indo-European language. Importantly, Turkish is not an Indo-European language. For those from a non-Indo-European language group, the reform had no effect on language but it increased their interactions with Germans to the same degree as for the Indo-European language users. 

Taking a wider view of the impact of this law in Germany, Ciro Avitabile, Irma Clots-Figuera, and Paolo Masella, the same economists mentioned above, published a peer-reviewed paper in the American Economic Journal: Applied Economics that looked at how child citizenship laws affected fertility decisions amongst immigrants. Fertility is influenced by culture, so many social scientists and economists think it is an important indicator of immigrant assimilation. Consistent with Gary Becker’s “quality-quantity” model of fertility, they found birthright citizenship reduced immigrant fertility and improved their health by reducing obesity and the social-emotional outcomes of the children affected. Again, the effects are small but citizenship reform moved immigrants closer toward German fertility and health norms.

Gathman, Keller, and Monscheuer also looked at fertility and family structure. They found that within 7.2 years of eligibility for citizenship, the immigrant-native fertility gap fell by 20 percent by raising the age of first births to immigrant mothers and reducing the likelihood of them having children. The citizenship reform also narrowed the marriage gap between German and immigrant women by 45 percent and German and immigrant men by 50 percent. Immigrant women were also more likely to marry men who were not from their own country of origin after the reform but the effect was small.

Felfe, Rainer, and Saurer found that immigrant parents enroll their children in preschool at a higher rate after the citizenship reform, closing the gap with native Germans. They also enrolled them earlier in primary school and pushed their children into the university track at higher relative rates. Further, reported “attention deficits” and “emotional problems” for the children of immigrants also decreased in schools relative to natives while there was no effect on reported “social problems,” “German language proficiency,” or “school readiness.” Another working paper by Felfe, Kocher, Rainer, and Siedler found that the educational achievement gap between young immigrant men and their native peers nearly closes due to the reform.

The granting of citizenship to immigrant children also reduces return migration, increases the rate of mothers stay at home with their children among the parents whose children were affected, and reduces or almost closes the trust gap between immigrant children and native children in behavioral experiments – virtually eliminating in-group favoritism for immigrant boys. 

The relatively few cases of citizenship laws changing in countries with large numbers of immigrants limit the opportunity to study how immigrants and their children are affected by birthright citizenship. The United States has not changed its policy on birthright citizenship in over a century so any attempt to study the impact of jus soli here would be constrained to cross-country comparisons. However, legal changes in Germany provided a quasi-natural experiment with the result that birthright citizenship slightly improves immigrant assimilation and integration but it is not, by any means, a panacea. The evidence from research on how birthright citizenship affects assimilation shows a generally positive impact and policymakers should assume that ending the practice in the United States will negatively affect assimilation here.