Protecting Their Own? The Real Reasons States Build Border Walls

Why do some nations build walls along their borders? In some cases, such walls are defensive structures aimed at blunting potential military incursions from a hostile neighbor, which was true for the Maginot Line between France and Germany, as well as for Great Wall of China. However, many of the world’s physical barriers occur along borders that have not been formally disputed. In a recent study, political scientists David Carter and Paul Poast explore the ways in which political economy impacts border instability and wall construction.

As illustrated in Figure 1*, 61 man-made border walls have been constructed since 1900. Many of these have been constructed since 2000. However, during this same timeframe, border instability has actually become less prevalent. This suggests that concerns about border security are not necessarily confined to military threats.

*Figure 1 was rendered with replication dataset files provided online by Paul Poast. One man-made border wall between France and the Netherlands from 1678 to 1814 has been omitted for want of horizontal space.

The authors assert that contemporary border walls work as policy measures that are primarily intended to help more developed states regulate the illegal flow of goods and people from less developed states. For instance, they state that the U.S. government initiated the construction of border walls along its wide southern border with Mexico in an effort to control access to its land and to prevent individuals from illegally crossing into the U.S. in search of better economic opportunities. In fact, the larger the economic inequalities between two nations, the more likely it is that a wall will be constructed between them. Thus, the authors hold that contemporary border wall construction is motivated primarily by concerns about economic security.

Cross-border economic disparities affect border instability in two ways. First, wage differentials lead some individuals to illegally migrate from low-wage states to high-wage states if the prospect of higher wages significantly outweighs the costs of migration. Second, price differentials motivate smugglers to traffic in contraband from low-paying states into high-paying states for profit maximization if the prospect of higher profits outweighs potential transaction costs.

Since economic disparity stimulates disparate opportunities and benefits across borders, adjacent countries with conspicuous differences in economic development tend to share unstable borders. The economic climate in each state translates to economic incentives at the individual level. Individuals are unlikely to run the risk of cross-border illicit activity if their own country and neighboring countries offer comparable socioeconomic opportunities.

The borders of North America illustrate this point well. Substantial wage differentials between the U.S. and Mexico generate flows of illegal immigration into the U.S. as individuals from Mexico search for more favorable economic opportunities. Sharp spikes in income disparities between the two states in the late 1980s and 1990s may have aggravated border instability and motivated the U.S. to construct border walls. More recently, President Donald Trump ordered the advancement and tightening of the measure in the name of “border security and immigration enforcement improvements.” However, this contrasts sharply with the situation along the border between the U.S. and Canada. Despite its massive length, the roughly similar levels of economic development between the U.S. and Canada appear to have sustained stronger border stability.

Carter and Poast hypothesize that the probability of a wall along the border between two countries increases as cross-border income inequality increases. The authors then identify two potential additional causes for border instability and wall construction: civil war and territorial disputes. Instances of civil war in a neighboring state increase the likelihood of border wall construction because refugees and insurrectionists often cross borders in search of sanctuary and a more secure environment. Territorial disputes between neighboring states therefore increase the likelihood of border wall construction as a means of deterring military threats.

The authors also attempt to explore additional linkages to border construction. Due to disparities in wealth between democratic and autocratic states, they assess different regime types in contiguous states in order to see the impact of regime type on wall construction. Other possible factors—including the capital-to-capital distance, military relationship, and the balance of military capabilities between adjoining nations—are also incorporated into the analysis.

Carter and Poast find that greater economic disparities between abutting states are associated with the wealthier state constructing a border wall between itself and its neighbor. Inflating the mean value of relative income inequality to be 50 percent higher than the actual mean value increases the probability of a wealthier state building a border wall by 34 percent. This strong correlation is consistently observed across all models used by the authors.

However, the authors find mixed results in the relationship between civil war, territorial disputes, and border wall construction. Civil war does not demonstrate a statistically clear effect on wall construction, and the presence of civil war in a neighboring state appears to be associated with a lower likelihood of wall construction. The authors posit that a neighbor’s civil war triggers severe violence and border instability, which in turn may dramatically increase the costs of erecting and maintaining a border wall. By contrast, the authors’ evidence regarding territorial disputes suggests that bordering states with territorial disputes are significantly more likely to build a border wall. However, prior territorial disputes do not have a clear positive impact on whether a border wall is currently present.

Carter and Poast therefore conclude that political economy is the most reliable predictor of contemporary border walls, in terms of both construction and continued presence. They also assert that democratic states are especially likely to build walls against autocratic neighbors. The findings confirm that post-Cold War border walls have been built to protect against unwelcome immigration and illicit transactions across the border.

Finally, Carter and Poast note that border walls are not necessarily a panacea for these concerns. Such expensive infrastructure projects may ultimately neither deter undocumented immigration nor uproot illegal trafficking; migrants and smugglers may simply reroute. For example, given the greater difficulty of trespassing borders that the walls pose, the role of professionals who specialize in eluding border controls and finding means of surreptitious entry may become more prevalent. This, in turn, drives up the likelihood of armed conflict among these professionals and national security forces. Unremitting instability at the U.S.-Mexico border illustrates the persistence of illegitimate cross-border flows in the face of harsher border control. Thus, border walls may not fully extirpate negative economic and security concerns along the border.

Article Source: Carter, David, and Paul Poast. “Why Do States Build Walls? Political Economy, Security, and Border Stability.” Journal of Conflict Resolution 61(2). (2017): 239-270.

Featured photo: cc/(Greg Bulla, photo ID: 813556790, from iStock by Getty Images)

Changwook Ju
Changwook (MPP '18) is a staff writer for Law & Politics. He is interested in political economy, civil-military relations, and electoral politics.

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