Migration Forces and Political Centralization: Insights from Emily Sellars

Authored By 
Rick Harrison
February 19, 2025

Worker in blue agave field in Tequila, Jalisco, Mexico with large mountains in the background rising into a bright blue sky

Before Emily Sellars went to graduate school, she served in Honduras with the Peace Corps and regularly spoke with people planning to emigrate to the United States.

“What caught my attention was people who would tell me there was no sense in trying, for example, to get a new park started in their community,” Sellars said. “They said the easiest thing for them was to go to the United States and send money home. There was a reliance on migration to deal with problems that arose in the community.”

This experience drove her scholarly pursuits, asking why migration took hold, how migration of neighbors affected an individual’s decision to migrate, and how migration might put more or less pressure on the government to deal with domestic problems.

A faculty fellow with Yale’s Institution for Social and Policy Studies and an assistant professor of political science, Sellars is nearing publication of two books. The first explores historical and contemporary forces driving emigration from Mexico. And the second involves the dynamics between political centralization and domestic conflict.

We recently spoke with Sellars about her work on how governments and people share the economic environment and how centuries-old forces continue to shape our world today.

ISPS: For your upcoming book, you studied emigration from Mexico to the United States for roughly the last 100 years. You build a theory that people with options to leave Mexico for a better life in the United States are less likely to invest in collective efforts to improve policies in Mexico. In turn, you suggest that, given these more attractive exit options, the entire Mexican society becomes less invested in addressing domestic issues because they anticipate fewer people will be around to help. What does this dynamic tell us about the intransigence of conditions in Mexico and the possibility for reform?

Emily Sellars: The book takes on the question of how having exit options like emigration affects the ability of a political system to reform. There are at least two schools of thought. A pessimistic view suggests that as people leave, there is less pressure on authorities to make improvements, and nothing will change.

ISPS: What’s a more optimistic interpretation?

ES: Another school of thought is that having options will put more pressure on the government to respond. Something like: If you don’t make improvements or address my concerns, I will leave. There are very different theoretical underpinnings to these two arguments.

ISPS: How so?

ES: Think about how things operate in a workplace. If you are trying to make change at work, there is an individual way: Do this or I’ll leave for another job. And a collective way: Let’s form a union and make demands. The effectiveness of strategies depends on how much those in power care about either individual exit or collective action. One person threatening to leave might matter a lot if that person is particularly valuable or influential. In other cases, a company might be happy to absorb the costs of turnover in exchange for getting rid of a troublemaker. Governments are often set up to react to collective action because they are collective enterprises. Emigration can be costly to those in power as well, but many governments have proven willing to let large numbers of their citizens leave without bearing much consequence.

ISPS: In the book, you explore why the Mexican government was more responsive to collective action than exit threats. Why might that be?

ES: Some of this has to do with features of the political context. As I discuss in the book, the structure and legitimacy of the post-Revolution Mexican government depended on at least the appearance of responsiveness to bottom-up collective action. Conversely, while some elites worried about the effects of large-scale emigration, there was a general willingness to accept the political and economic costs of letting citizens leave. One important factor in understanding the politics of emigration is that the consequences of exit spread beyond those who can leave. Even if you can’t or don’t wish to emigrate, knowing that your neighbor might leave changes your own political expectations and behavior.

Emily Sellars

ISPS: How does that dynamic play out?

ES: Collective action requires cooperation between groups of individuals. The success of a protest, a petition, or a strike often depends on how many others join in some action. Whether you are a citizen unhappy with your political situation, a worker unhappy with your employer, or a parent unhappy with your local public schools, your best course of action differs based on how you think others will behave. If you think others might be willing to join in pushing for improvements together, that might be the best option. If you think everyone else is looking for an exit option to address the problem — whether moving to a new political jurisdiction, changing employers, or sending your child to private school — then you might feel pushed to do the same. You don’t want to be left trying to improve the situation collectively if others are not going to invest in the process with you.

ISPS: But does everyone have exit options? Not everyone can pay for private school, and not everyone has the resources to emigrate from Mexico, at least not securely.

ES: No, not everyone can exit or opt out. It is often, though not always, more privileged people who have that option. In the case of 1920s Mexico, typical emigrants were not the poorest Mexicans but somewhere in the middle economically, and they were clustered in a few geographic regions. This evolved somewhat over time, but even at the peak of Mexico-U.S. migration in the 1990s and early 2000s, emigration was widespread in some places and prohibitively costly in others.

ISPS: Clearly there is also a difference between who is forced to leave and who has the option of leaving.

ES: Absolutely. The book looks at a context of mostly “voluntary” migration, but it also asks what it means to be “forced” to leave. Perhaps there is no work in my community, so I feel compelled to leave, even if this is not at the point of a gun. One of the observations that motivated this project was that people often speak of having “no choice” but to emigrate, even in contexts where we’d usually see migration as voluntary. The theory of the book explores how expectations about emigration or the likelihood of reform can become self-reinforcing. As others choose to leave, individual exit comes to be seen as the natural — and perhaps only — pathway to improvement.  

ISPS: Leaving behind those who most desperately need change at home.

ES: Right. Not everyone can leave, and emigration can make it more difficult for those who remain to organize. This is something that I’ve become really interested in since starting this project. How does exit affect the people who can’t leave? How does emigration change their interests and perceptions?

ISPS: What role does U.S. policy have in this dynamic?

ES: Mexico-U.S. migration has been occurring for over a century and will continue. Part of what I’m looking at in the book is how U.S. policy changes have influenced the availability of exit options for Mexican citizens. There have been a few distinct phases. One is the relatively open system that prevailed up until the Great Depression. The border was sparsely monitored, especially prior to the mid-1920s. That’s one extreme.

ISPS: What came next?

ES: During the Depression, there was a major wave of deportation and return back to Mexico. Then came the Bracero Program. Starting in 1942, this was a series of bilateral treaties to bring people into the United States as temporary laborers. This program evolved over time and was punctuated by a series of immigration crackdowns, for example, in the early 1950s. That phase ended in 1964, starting a generation-long pattern of largely unauthorized or irregular migration. In the 1980s and 1990s, there was a shift toward more militarization and regulation of immigration, which raised the human toll of emigration without slowing it. Many of these changes occurred as a function of U.S. policies and priorities, but the impacts spread. Every election cycle in the United States reverberates into these small Mexican communities. One of the things I show in the book is that periods of greater immigration restriction often saw more local collective action and reform within Mexico but sometimes more repression as well.

ISPS: You and a co-author are working on a new book about the relationship between political centralization and domestic conflict. You explore the tradeoffs to consolidating power in a central government, which can increase financial and military strength of the state but also alienate allies needed to maintain control within the state, especially away from the center of power. You derive your evidence from over 400 years of Mexican history. How challenging is it to find a shared thesis across such different cultures, governments, and historical periods?

ES: Definitely challenging. The empirical part involves tracing the internal organization of the state over a long period of time, from the late Aztec period through the 20th century. This requires some work in gathering data from historical sources as well as some thinking about how well our theoretical concepts translate across time periods. A lot of my work is historical, and the same is true of my coauthor on this project, Francisco Garfias of the University of California, San Diego. As social scientists, we are in the business of learning about the world as it exists, as it has existed, and as it probably will exist in the future.

ISPS: What can you learn about state building dating back to the Aztec period, when it was so different?

ES: It is true that states and societies have changed a lot over the centuries. Technologies have certainly changed a lot. What has not changed, we argue, is one central problem of political control. States and rulers face a choice in how much to consolidate power themselves or how much to devolve to others, such as local elites, traditional leaders, or religious authorities who have independent standing in a community. This book is about how central rulers over time have made very different choices over whether and how to consolidate control within the state and how these choice are influenced by the threat of domestic conflict.

ISPS: What influences that dynamic?

ES: We argue that there is a dilemma facing central rulers. They need to consolidate enough authority to effectively rule but not so much that the political system becomes vulnerable to defection from within. Over time, political leaders in Mexico have made different calculations in how to balance these threats. Some eras saw aggressive efforts to build the capacity of the central government. In others, leaders kept the central government relatively weak. Either choice had important implications for the stability of the political system.

ISPS: What is the connection to political stability or conflict?

ES: The academic literature often emphasizes how weak states are prone to conflict. When the central government is very weak, it cannot effectively mediate conflict between rival groups or between rival groups and the state. A stronger state can more easily deploy force against rivals, but there is a risk in building the strength of the central government. Consolidating power or resources usually means taking it from someone, and those who lose out might defect or lash out against the state in a later crisis. In other words, state building can backfire by increasing the risk of defection from within. The three major episodes of punctuated state collapse that we examine in the book — the collapse of the Aztec state, the War of Independence, and the Mexican Revolution — were in fact all preceded by major efforts to increase the strength or capacity of the central government.

ISPS: And this dynamic has not changed significantly over time?

ES: The precise character of the tradeoff has certainly changed over time, but the tradeoff still exists. Technology can increase a central government’s ability to monitor far-flung places, for example, and it has certainly changed the style and form of warfare. But in tracing Mexico’s political development through the precolonial, colonial, postcolonial, and post-revolutionary periods, it is interesting to note how governments in all of these periods faced similar tradeoffs in determining how much to consolidate additional power in the center or how to get groups who might not be aligned with the government to buy into the political system. The specific policies, programs, and institutions changed a lot over time, but the central tension that we highlight is strikingly similar across eras.

ISPS: Immigration was a huge topic during the most recent election. Do you think most people understand the issue? What would you like the average voter to know?

ES: When it comes to Mexico, I don’t think people have adjusted for the fact that migration patterns have evolved considerably since the 1990s. Many of those who come through Mexico to the United States come from other places, such as Central America, Haiti, Venezuela, or even Ukraine or West Africa. I also think that people tend to conflate stocks and flows when it comes to migration.

ISPS: What do you mean?

ES: There are a large number of Mexican citizens living in the United States, for example, but the net migration rate between the two countries is much smaller that it was in the 1990s, even negative in some years.

ISPS: I see. What else?

ES: Finally, I think it’s hard for people to understand some of the complicated issues that arise in regulating migration. I think that some people have an impression that border security is lax or officials have not invested in monitoring immigration. In fact, the southern border is as heavily policed now as it has ever been, thanks in part to the efforts of the Mexican government on the other side of the border. More generally, the long history of Mexico-U.S. migration shows that investing in border security or immigration crackdowns does not stop migration permanently or do much to address the root causes leading people to move.

ISPS: And, as you have found, migration policies when implemented can have broader consequences on politics.

ES: That’s right. We think of emigration as an individual decision driven by big external pull factors, such as a desire for better living standards or higher wages. Or push factors, such as poor political or economic conditions at home. But I like studying this subject because it’s not so simple. People are embedded in communities, so individual migration decisions depend on the choices of others, and they have impacts beyond a single person or family. As I discuss in the book, it is often hard to classify these impacts as “good” or “bad.” When it comes to complex topics like migration, if you think that there is an obvious or easy answer to some question, you are probably not thinking hard enough.

Area of study 
Immigration