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Since the early 1990s, more than 230 tunnels have been officially discovered along the U.S.-Mexico border, with the highest concentration found in California and Arizona. These regions, particularly around San Diego and Nogales, have become hotspots due to favorable soil conditions that facilitate the construction of such structures. The widespread use of tunnels underscores their importance to cartels’ smuggling operations, serving as concealed routes that enhance their ability to evade law enforcement.