Through-trailer service (caja corrida) moves freight door to door in a single trailer: the trailer is loaded once at origin and unloaded once at destination, while tractors and drivers swap at the border via a transfer. It is the backbone of modern door-to-door cross-border service.
Through-trailer service, caja corrida in Mexican trucking Spanish, is the model where one trailer carries the load the entire way. Loaded and sealed at origin, the trailer runs the Mexican leg behind a Mexican tractor, crosses the border behind a transfer tractor, and finishes the U.S. leg behind a U.S. tractor (or the mirror image southbound). The freight itself is touched twice: once loading, once unloading.
This is the mechanic behind door-to-door cross-border service, and it displaced transloading as the default for most dry freight because it is faster at the border, cheaper in handling, and dramatically better on claims.
Through-trailer is usually what your customer wants, and it comes with structural requirements worth understanding. The trailer crosses jurisdictions, so trailer interchange agreements govern who is responsible for the equipment on each leg, and someone's trailer spends days away from its owner, which is why empty return economics and trailer detention at the border show up in pricing. Seal integrity is the through-trailer's superpower: one seal from dock to dock, verified at each handoff. Protect it, because a customs exam can still open the trailer, and the reseal must be documented down the chain. When comparing quotes, confirm the service is genuinely through-trailer rather than a transload described optimistically. For the full model, see the Mexico 101 Guide.
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