Barriers to Entry: Who Builds Fortified Boundaries and Are They Likely to Work?

The passion with which both proponents and opponents of the US-Mexico border wall cling to their views is surprising given how little we actually know about when such walls are effective and what drives states to build them. Our goal in this preliminary study is to begin examining these questions. First, we elaborate the concept of “fortified boundaries,” which are asymmetrical, physical barriers for the purposes of border control. These boundaries are more formidable in structure than conventional boundary lines but less robust than militarized boundaries. The states that construct fortified boundaries tend to do so unilaterally, to prevent the flow of peoples or goods into their territory from a neighboring state that does not share parallel concerns. Second, we briefly review the literature pertaining to fortified boundaries, and offer some preliminary speculation on the reasons why such boundaries might actually succeed in impeding cross-border human flows. We argue that although in some cases fortified boundaries may indeed lead to blowback effects on the state erecting the boundary, more generally such boundaries slow the flow of would-be entrants by raising the cost to those entrants of attempting to cross the border. Third, we introduce a novel dataset that includes all post-1945 fortified boundaries worldwide, a total of 28 cases, and identify salient commonalities and differences across them. Among other things, we show that whatever the arguments against such barriers, states continue to build them, and at an accelerating rate. Three-quarters of all post-World War II barriers have been initiated since 2000. Moreover, several of these barriers cover greater distances, traverse more challenging terrain, and place a far greater burden on the finances of the initiating states than the proposed U.S.-Mexico border fence.