Since 2000, 3,199 human remains of unauthorized migrants have been recovered from the Sonoran Desert of southern Arizona (Coalición de Derechos Humanos 2018). These recovered remains provide only one indicator of the scope of death and suffering affecting unauthorized migrants and their loved ones — something that also includes thousands of individuals whose whereabouts or remains are never encountered (and who therefore remain disappeared) (ibid.). Just as significantly, the number of human remains recovered in southern Arizona has remained consistently high despite a significant decline during the past decade in the number of apprehensions (a figure frequently used as a proxy for unauthorized migration) in the Border Patrol’s Tucson Sector. This condition has led scholars and commentators alike to observe an increase in the ratio of deaths to migration, even as unauthorized border crossing fluctuates (Martínez et al. 2014; Reineke and Martínez 2014; International Organization for Migration 2018).
In 2012, the southern Arizona humanitarian organization No More Deaths began systematically tracking the use and vandalism of cached drinking water it supplies at 512 sites across an 800-square-mile area of southern Arizona’s Altar Valley, a high-traffic migration corridor bisected by the US–Mexico border (Ferguson, Price, and Parks 2010; Regan 2010; Boyce 2016; Chambers et al. 2019). On an almost daily basis, volunteers with No More Deaths travel this migration corridor to resupply caches of 5–20 gallons of clean drinking water, physically hauling this water by truck and by foot. Each cache site is tracked using a Global Positioning System (GPS) coordinate to make navigation of the remote desert borderlands and the location of dispersed and frequently hidden cache sites easier for new volunteers.
In 2015, the authors began working with No More Deaths to digitize and conduct spatial and statistical analysis on the data entered into these desert aid logs, with the express aim of seeing what this archive can reveal about everyday activity related to boundary enforcement and migration, as well as the efficacy of the organization’s activities throughout time. In total, No More Deaths’ desert aid archive contains 4,847 unique entries from March 2012 to December 2015, logging the date when an individual cache site was visited, the number of new water gallons deposited during this visit, the number of water gallons encountered intact and unused from previous resupply visits, the conditions of any empty water bottles left behind (including telltale signs of human vandalism, as well as occasional animal damage), and any subjectively unusual conditions or noteworthy events that were observed at the site or during the visit.
Combined, this archive provides remarkable and uncommon insight into subtle changes in migration routes and patterns within the Altar Valley desert corridor, as well as those quotidian forms of harassment and vandalism of water supplies that we believe are intended to amplify and maximize hardship for unauthorized border crossers. Indeed, scholars have long argued that the US Border Patrol’s enforcement strategy of “Prevention Through Deterrence” (PTD), first launched in 1994, is premised on instrumentalizing the difficult climate and terrain of the US–Mexico border by pushing migration routes away from traditional urban crossing areas and into increasingly rugged and remote desert areas (Andreas 2001; Cornelius 2001; Rubio-Goldsmith et al. 2006; Nevins 2008; Martínez et al. 2014; De León 2015; Slack et al. 2016). The Border Patrol’s own policy documents make this case. Observing that migrants “crossing through remote, uninhabited expanses of land and sea along the border can find themselves in mortal danger,” the Immigration and Naturalization Service (INS — at the time, the Border Patrol’s parent agency) argued that by channeling migration routes into “harsh terrain less suitable for crossing and more suitable for enforcement,” the Border Patrol would eventually obtain a “tactical advantage” over would-be border crossers (INS 1994, 7). Then–INS Commissioner Doris Meissner later reflected, “We did believe that geography would be an ally for us. It was our sense that the number of people crossing through the Arizona desert would go down to a trickle once people realized what [it’s] like” (quoted in Cornelius 2005).
In this article, we conduct geospatial modeling and statistical analysis of No More Deaths’ desert aid archive. This involves measuring changes in the distribution of water use throughout time across the 62 cache sites consistently visited during all four calendar years included in the dataset, and then reading this measurement against a model of ruggedness that incorporates multiple variables including slope, vegetation, “jaggedness,” and ground temperature while controlling for Euclidian distance. Adjusting for seasonal variation and the overall volume of water use, we find a statistically meaningful increase in the cumulative ruggedness score of migration routes associated with cache sites during the four calendar years included in No More Deaths’ desert aid logs. These findings reveal a steady pressure toward more rugged and difficult crossing routes throughout time, an outcome that provides important context for the vandalism and harassment that target migrants and humanitarian aid workers alike (see No More Deaths and Coalición de Derechos Humanos 2018).
In what follows, we first provide greater detail on the context of our study and of the authors’ collaboration with No More Deaths. Next, we discuss our research methodology, including the contours of the geographic information system (GIS) modeling through which we conduct our analysis. We then present our findings, and discuss and contextualize these, before turning to some of the limitations of our study and directions for future research. We conclude by considering some of the policy implications of our findings, as well as their implications for studies of mobility, border policing, and state violence, including in contexts when states are instrumentalizing environmental features and conditions for the purposes of boundary enforcement.