Abstract: A cargo transportation system comprising secure (fully closeable and lockable), sealable, stackable, trackable, universal, auto-latching “pallet boxes” that may be used in two main ways: 1) secured to the undercarriage transverse I-beams of over-the-road semi-trailers by means of loading alignment and hanger assemblies that provide positive locking-in-place; and 2) stackable, up to three or more high, inside the trailer bodies. The inventive pallet boxes are designed to be secured by auto-latching hanger assemblies that are retrofittable on individual types of semi-trailer undercarriages, both US and metric (European, Central and South American, and Asian) standard dimensions. The pallet boxes include vertical sidewall load-bearing channel members permitting stacking fully-loaded pallet boxes three or more high. The pallet boxes may be refrigerated, insulated, or atmospherically controlled, e.g., chargeable with preservative, security or disinfecting gases, during shipping.