Francesca Mazzolari hypotheses that the significant rise in naturalization rates in the 1990s were attributed not to welfare and immigration reform, but rather changes in dual citizenship laws that allowed citizens to naturalize in the United States without surrendering their nationality of origin. To test this hypothesis, he uses micro data from the 1990 and 2000 U.S census to conduct a quasi-experiment in which he compares the naturalization rates from five countries that recently changed there naturalization laws (the Dominican Republic, Costa Rica, Brazil, Colombia, and Ecuador) with a control of other Latin American countries. He conducts a difference-in-difference analyses in which he ensures differences in origin are constant overtime and outcomes are constant across an origin group. The results are that the treatment group with the change in citizenship laws positively affected the U.S Naturalization rate as much as ten percentage points during the 1990s compared with the control.
In order to rule out other factors that contributed to the rise in naturalization in the 1990s, Mazzolari analyzes this data based on socio-economic differences and concludes from individual data from the 1990 to 2000 censuses that dual citizenry laws are the only systematic difference that would effect naturalization rates. He argues that if naturalization was sought after because of welfare benefits, then more people should of naturalized in states that had welfare programs. Also, if the welfare theory was true, personal characteristics like education and gender, which predict welfare eligibility in the United States, should appear in this data, but the only systematic difference during this ten year period is the changes in dual citizenry laws and the subsequent rise in naturalization rates from the five Latin American countries that changed their laws. Thus, Mazzalori rules out other incentives to naturalize and confirms his hypotheses that there is a positive correlation between changes in dual citizenry laws and naturalization rates which contributed to the rise of naturalization rates in the 1990s.
Mazzaolari is not just concerned with the positive correlation in changes of dual citizenry laws with naturalization rates and the subsequent rise in naturalization rates. He also looks at economic assimilation and the jobs of those who naturalized, and relative employment and earning gains that exist among those who naturalize. For example, immigrants from countries that recently granted dual citizenship rights experienced a 3.6 percentage point increase in full time work relevant to other latin american countries (19). They also experienced a 1.5 percentage decrease in receive income supplementation and if on welfare a 17 percent relative drop in payments (20). Additionally, immigrants from the treatment group who earned a high school diploma experienced an earning increase of 2.5 percent (20). Thus, immigrants from countries who changed their dual...
