Rate of Aquatic and Maritime Drowning Deaths After US-Mexico Border Wall Height Increase

Abstract

This study assesses migratory drowning deaths along the southwest border of the US before and after the increase in border wall height.

In December 2019, the US finished its initiative to increase the height of the US-Mexico border wall from 5 to 9 m (17-30 ft) along 640 km (400 miles) of southern borderlands, in accordance with executive order 13767.^1,2 This height change has been associated with an increased rate of severe injuries seen by trauma surgery departments in San Diego, California.^2,3,4,5 We hypothesized that this increase in injury risk may have encouraged more migrants to pursue aquatic and maritime migration routes via the Pacific Ocean and other nearby bodies of water, swimming, floating, or traveling across the international border in boats or other personal watercraft, resulting in an increased incidence of drowning deaths in the region. In this study, we assessed migratory drowning deaths along the southwest border of the US before and after the increase in border wall height.

Methods

Data collected by the International Organization for Migration’s Missing Migrants Project (MMP) were analyzed across two 4-year periods (2016-2019 and 2020-2023). The MMP’s annual mortality reports (which compile data on refugees, migrants, and asylees who die or go missing during migration) for the North American region were filtered for drowning deaths along the US-Mexico border and categorized according to the body of water in which they occurred: the San Diego region of the Pacific Ocean, canals (including the All-American Canal in southeastern California), and other bodies of water (lakes, streams, drainage ditches, and washes). These drowning rates were compared with those in the Rio Grande, along which the wall is largely absent.⁶

The MMP contains data from official sources, such as law enforcement and nongovernmental organizations, as well as unofficial sources, such as media reports and interviews. All data included in the database are subject to published data collection guidelines, and each source is rated for source quality on a scale from 1 to 5, with 1 being a report from a single news source and 5 being a report from an official source (such as the US Customs and Border Patrol). The data analyzed in this study had a mean (SD) source quality rating of 3.7 (1.6). Data on injuries related to maritime and aquatic migration that did not result in drowning deaths were not included in the MMP. Analyses were descriptive, and Microsoft Excel, version 16.77 was used. Based on the publicly accessible nature of the data source, this project was exempted from institutional review board approval by the University of California, San Diego.

Results

From 2016 to 2019, the MMP recorded 1 drowning death in the San Diego region of the Pacific Ocean, and from 2020 to 2023, 33 drowning deaths were recorded for an overall increase of 3200%, which was calculated as follows: (33 − 1)/|1| × 100 = 3200. Drowning deaths in canals increased from 49 to 64 (a 30.6% increase), and drowning deaths in all other bodies of water increased from 15 to 35, an increase of 133.3%. Along the Rio Grande, 97 persons were reported drowned during the period from 2016 to 2019, and 96 persons were reported drowned during the period from 2020 to 2023, an overall change of −1.03% (Table).

Table. Drowning Rates Across the US-Mexico Border During Two 4-Year Periods^a.

Period	No. of drowning deaths
	Pacific Oceanb	Rio Grande	Canalsc	Otherd
2016-2019	1	97	49	15
2020-2023	33	96	64	35
% Changee	3200	−1.03	30.6	133.3

^a Before and after the completion of the border wall–height increase project along the US-Mexico border.

^b Limited to drownings occurring in the area immediately bordering the international border (San Diego County).

^c Includes the All-American Canal, which follows the international border for approximately 128 km (80 miles) in Imperial County, California.

^d Includes drainage ditches, streams, washes, and lakes.

^e Calculated as (2020-2023 value − 2016-2019 value)/|2016-2019 value 1| × 100.

Discussion

There were more aquatic and maritime drowning deaths of migrants along the southwest border of the US during the period after the height increase of the US-Mexico border wall compared with the period prior to the height increase. This height increase has previously been associated with increases in traumatic injuries due to falls,^2,3,4,5 and these results represent a further potential consequence to the increase in wall height and a relevant consideration for immigration policymakers, first responders, and emergency departments in the area.

Study limitations include the lack of data on the baseline numbers of illegal migrants which were affected during the last 8 years by geopolitical conflict, the COVID-19 pandemic, and Title 42 (a US public health order from 2020 to 2023 that allowed immigration authorities to expel refugees and asylum seekers during the pandemic), and the relative rarity of drowning as an outcome. In addition, the quality of the data was moderate because they were based on reports from multiple sources and did not include data on migrants who drowned but were not found.

Section Editors: Kristin Walter, MD, and Jody W. Zylke, MD, Deputy Editors; Karen Lasser, MD, Senior Editor.

Supplement.

Data Sharing Statement