• Zhu, J.L., Chau, N., Rodewald, A., and Garip, F. (2024). "Weather Deviations Linked to Undocumented Migration and Return between Mexico and the United States." Proceedings of the National Academy of Sciences (PNAS).

As the world’s climate continues to change, human populations are exposed to increasingly severe and extreme weather conditions that can promote migration. Here, we examine how extreme weather influences the likelihood of undocumented migration and return between Mexico and the United States. We used data from 48,313 individuals observed between 1992 and 2018 in 84 Mexican agricultural communities. While controlling for regional and temporal confounding factors, we related individual decisions to migrate to the United States without documents and subsequently return to Mexico with lagged weather deviations from the historical norm during the corn-growing season (May to August). Undocumented migration was most likely from areas experiencing extreme drought, and migrants were less likely to return to their communities of origin when extreme weather persisted. These findings establish the role of weather shocks in undocumented Mexican migration to, and eventual settlement in, the United States. The findings also suggest that extreme weather conditions, which are likely to increase with climate change, promote clandestine mobility across borders and, thus, expose migrants to risks associated with crossing dangerous terrain and relying upon smugglers. 

• Zhu, L., Hall, M., and Matsudaira, J. (2020). "Immigration Enforcement and Employment in Large Firms: Evidence from County Participation in 287(g)." In B. Jivetti and M. N. Hoque (Ed.), Population Change and Public Policy. Springer.

In this chapter, we examine the effect of 287(g) on employment in large firms, separately for Hispanic and white workers. Using the data on county-level 287(g) applications and establishment-level employee data from the Equal Employment Opportunity Commission, we employ a difference-in-differences identification strategy, comparing employment outcomes of establishments in 287(g) implemented counties to those in 287(g) denied counties, before and after the implementation of 287(g). Overall, we find that 287(g) has significant and negative impacts on both Hispanic and white employment. The effects are concentrated in a few selected industries; for Hispanic workers, agriculture and mining, health care/social services, and accommodation/food services suffer the largest negative impacts, while for white workers, the adverse employment effects are mostly concentrated in wholesale and retail trade, as well as in administrative support/waste management and the health sectors. We also find that 287(g) differentially affects Hispanic and white workers by gender. For Hispanic workers, most of the effects are driven by male employment, consistent with the fact that deportation in the interior U.S. disproportionately impacts Hispanic men more than Hispanic women. For white workers, on the contrary, both male and female employment are negatively and statistically significantly affected by the implementation of 287(g).

• "The Career Effects of Union Membership." (with Samuel Dodini, Kjell Salvanes, and Alexander Willén) [IZA Discussion Paper No. 16185] 

We combine exogenous variation in union membership with detailed administrative data to estimate the career effects of labor unions. We examine through which channels unions influence worker outcomes, whether unions influence workers differently across workers' careers, and the overall lifetime insurance value of union membership. Our results highlight that the career effect of union membership differs greatly depending on the age at which workers enroll, with younger workers benefiting more via wages and older workers benefiting more via job protection and promotions. When combining all effects through these channels, the long-run effects of union membership on total earnings are relatively consistent over the life cycle. We show that focusing on a restricted set of outcomes, such as wages and employment, generates a fractionalized understanding of the multidimensional career effects that union membership has on workers.​

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• "Comparative Immigration Policies and the Resource Effects of International Students in U.S. Higher Education." [PDF] Reject and Resubmit, American Economic Journal: Economic Policy

This paper studies the causal effect of resources in the context of U.S. higher education, exploiting an exogenous resource shift brought on by international students. I leverage a restrictive immigration policy change in the U.K. that induced more students from former British colonies to enroll in U.S. universities. I find more international enrollment leads to more domestic completion, especially in public four-year institutions. Additionally, I find positive cross-degree-level effects of international students in master’s degree programs on domestic students in bachelor’s degree programs. The positive impact is most likely through cross-subsidization of tuition, serving as evidence of resource effects.​

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• "Union Membership and Native-Immigrant Labor Market Gaps." (with Samuel Dodini and Alexander Willén) [PDF] Revise and Resubmit, The Economic Journal

We examine the role of unions in shaping the labor market gaps between natives and immigrants. We do so by combining rich Norwegian register data with exogenous variation in union membership obtained through national government policies that differentially shifted the cost to workers to join a union. While union membership significantly improves the wages of natives, its positive effects diminish substantially for Western immigrants and disappear almost entirely for non-Western immigrants. The effect of unions on native wages, and the role of unions in augmenting the native-immigrant wage gap, is nonexistent in competitive labor markets while it is substantial in markets characterized by a high degree of labor concentration. This implies that unions act as a countervailing force to employer power in imperfect markets and can ameliorate the negative labor market effects of labor market concentration, but only for natives. By surveying native and immigrant union members, we show that the differential labor market effects of unions across nativity status likely operate through the behavior of unions rather than through differences in how natives and immigrants utilize their unions.

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• "Climate Change and Migration: Cumulative and Heterogeneous Migration Response to Weather Fluctuations in Mexico." (with Filiz Garip) 

This paper studies the effect of rainfall and temperature shocks on Mexico-U.S. migration using data from 97,732 individuals in 152 origin communities between 1991-2018.  We find that an extreme decline in annual rainfall from the local mean increases the likelihood of first migration. Wet, hot or cool shocks have no apparent effect. The drought effect is concentrated in rural communities with little irrigation and especially large in corn-producing regions experiencing rainfall deficits during the growing season. The drought effect intensifies over time. Two consecutive years of low rainfall create a migration response that an isolated year of drought does not. The cumulative effects also vary by household wealth. Better-off households respond immediately to adverse conditions while the poor only migrate after experiencing consecutive and worsening weather shocks. These findings suggest that weather-related migration pressures can be relieved through an immediate intervention after a single year of drought and through long-term investments in irrigation in agricultural communities of Mexico. ​​​

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• "Effect of U.S.-Canada Comparative Immigration Policies on Immigrant Inflow and Labor Markets in Canada."

Current U.S. immigration quota system that imposes limits on the number of green cards based on nationalities has not changed since 1991, while demand has increased exponentially. This results in long wait times for individuals from high demand countries. For employment-based green cards, in recent years, college-educated workers from India need to wait for over a decade before submitting applications. In contrast, Canada has implemented several favorable immigration policies to attract high-skilled immigrants. In this paper, I examine the effect of comparative immigration policies in the U.S. and Canada on immigrant inflows and labor market outcomes in Canada. I first show that the adoption of Express Entry, Canada's point-based immigration program, significantly increases new economic immigrants from India. I then estimate the labor market impact of new immigrants using an instrumental variable strategy. Preliminary results show that the surge of new immigrants does not negatively affect employment in local labor markets.​​​

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• "The Risk of Being Deported: Deportation Prevalence among Unauthorized Immigrants in the interior U.S."

Deportation of unauthorized immigrants has increasingly become one of the most heated topics in the U.S. However, little is known about cumulative deportation risk one faces. Using 2006-2013 U.S. deportation data and synthetic cohort life table method, this study estimates the cumulative probability of interior deportation for unauthorized immigrants in the U.S. over time and by gender. The results show that, depending on the examined year, estimated length of stay, and age window of stay, an unauthorized immigrant in the U.S. faces up to 28% cumulative probability of being deported, which is far higher than commonly thought. Compared to the point-in-time deportation rates, the cumulative risks portray a completely different picture for the unauthorized immigrants facing deportation. Moreover, the deportation risks diverge drastically by gender – across all analysis years, men at all ages have higher deportation prevalence than women – and the gap can be as large as 12 times depending on the year. The gender disparity in deportation risk has important and serious implications for Hispanic children’s wellbeing as well as inequality in the society.​​​

• "International Students and Natives’ Attitude towards Immigration: Evidence from Administrative and Experimental Data." 

Across the world, immigration has been transforming many countries' demographics in the past decades, which has crucial implications on future politics and the policy-making processes of many developed democracies. In this paper, I examine the causal effect of international students on local communities' attitudes towards immigration. By using administrative data of the universe of international students in the U.S. from 2001 to 2015 and an instrumental variable identification strategy, I am able to isolate the labor market competition hypothesis in immigration attitude formation, and focus exclusively on the sociopsychological hypothesis. The preliminary results show that overall, an increase in the share of international students at the county level results in marginally more conservative immigration attitude of natives. Interestingly, this effect is driven entirely by individuals with democratic party identity.​​

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• "Intergenerational Mobility and Human Capital: Evidence from Three Generations." (with Sadegh Eshaghnia and Kjell Salvanes)​

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• "Direct and Spillover Effects of DACA: Evidence from Consumption Patterns and Labor Market Outcomes." (with Rene Crespin)​​