What documented instances exist of law enforcement finding tunnels used for drug smuggling in the U.S.?
Executive summary
Law enforcement has repeatedly documented cross‑border subterranean drug‑smuggling tunnels along the U.S.–Mexico frontier, especially in southern California and Arizona, with multiple high‑profile discoveries in 2020 and 2024–2025 that ranged from short shafts to multi‑thousand‑foot passages equipped with rails, ventilation and electricity [1] [2] [3] [4]. Agencies including CBP, ICE/HSI, DEA and joint Tunnel Task Forces have seized tons of narcotics from these tunnels and reported dozens to more than 75 detections in recent years, though enforcement officials note tunnels are a shrinking — albeit still significant — part of cartel smuggling strategies [5] [3] [6] [7].
1. The headline finds: long, sophisticated San Diego‑area tunnels
Beginning in 2020 and recurring through 2025, federal authorities disclosed the discovery of unusually long and technically advanced cross‑border tunnels in the San Diego/Otay Mesa corridor — including what CBP and news outlets described as the “longest” ever found, a roughly 4,309‑foot passage with rail, ventilation, drainage and electrical systems connecting Tijuana to San Diego [1] [2]. A separate 2020/2021 period saw task forces uncover another sophisticated tunnel with a rail system and multiple drug seizures, and in 2025 CBP announced an unfinished nearly 3,000‑foot tunnel extending from a Tijuana residence under the Otay Mesa Port of Entry that was actively under construction when detected [8] [7] [4].
2. Quantities seized and the multi‑agency response
When tunnels have yielded contraband, seizures have been large and mixed: a 2025 San Diego Tunnel Task Force operation reported confiscating roughly 1,300 pounds of cocaine, 86 pounds of methamphetamine, 17 pounds of heroin, about 3,000 pounds of marijuana and over two pounds of fentanyl from a single tunnel discovery [5]. Those operations are typically led by joint units — HSI, Border Patrol, DEA and U.S. attorneys’ offices — and followed by physical remediation such as filling tunnels with concrete to render them unusable [5] [9] [4].
3. Not limited to one era or place: Nogales, San Luis and Mexicali examples
Tunnels are not new nor exclusive to San Diego; historical and archived reports cite multiple finds in Arizona and other border cities. Examples compiled by agencies and reporting include a 1,300‑foot unfinished tunnel discovered near San Luis, Arizona, in 2020, and several tunnels detected near Nogales in 2012 and 2014, some equipped with electricity and ventilation and used to move marijuana and other drugs [10] [11]. ICE and HSI press releases also record shorter but operational tunnels found in Mexicali and Calexico in different years [12].
4. How common are tunnel discoveries — and the trendline
Federal officials have said they detected more than 75 cross‑border smuggling tunnels in a recent four‑year span, with most discoveries concentrated in California and Arizona and multiple large‑scale tunnels found in San Diego since 2006; CBP has also noted dozens of detections in San Diego alone dating back decades [3] [6]. At the same time, some federal investigators and reporting frame tunnels as a declining method compared with concealment through ports of entry for small payloads like fentanyl, though cartels may still invest in tunnels when other routes are constrained [7].
5. What the record shows — and what it doesn’t
The documentary record across CBP, ICE/HSI, DEA and mainstream outlets demonstrates numerous verified instances — from short, 100–200‑foot passages to multi‑thousand‑foot engineered tunnels — used or intended for large‑scale narcotics smuggling into the U.S. [4] [5] [1]. Public reporting and agency releases provide strong evidence of seizures, construction features and remediation actions, but the available sources do not provide a complete inventory of every tunnel ever found, nor do they fully disclose the criminal networks behind each shaft beyond general attribution to transnational drug trafficking organizations [3] [8].
6. Alternative perspectives and enforcement implications
Law enforcement emphasizes tunnels as proof of cartel sophistication and justifies interagency task forces and infrastructure remediation [9] [13], while analysts quoted in reporting caution that tunnels are expensive and therefore relatively rare compared with other smuggling methods — a point that tempers claims that tunnels are the primary avenue for drugs entering the U.S. [7] [8]. The pattern in the reporting is clear: tunnels remain a documented and occasionally massive conduit for drugs where detected, even as their overall role in cartel logistics fluctuates with enforcement and market pressures [5] [6].