TIJUANA, Mexico — Squatting and sweating inside the latest drug tunnel found here in this Pacific border city, it was easy to understand the amazement expressed by Mexican and American officials. This one was a stunner.

The tunnel ran for almost half a mile, with wooden planks holding off the earth on all sides. Energy-saving light bulbs illuminated the route. A motorized cart on metal rails ensured quick passage, while a steel elevator hidden beneath the floor tiles in a warehouse made the 40-foot descent to the tunnel’s entrance feel like the slow drop into an unregulated mine shaft.

And yet, here is the simple fact obscured by superlatives like “the most elaborate” and “the most sophisticated,” which officials seem to lather on each new find.

Tunnels are Tijuana. They have become an inevitable, always-under-construction or always-operating part of city life, as entrenched as cheap pharmacies and strip clubs.