QUOTE: Originally posted by cacole There is a border crossing point at Nogales, on the U.S. / Mexican border south of Tucson, where the UP interchanges traffic with NdeM. This is primarily traffic to and from a Ford Escort assembly plant in Hermosillo, Mexico. From what I have heard about this operation, Union Pacific crews are allowed to pull Mexico-bound rolling stock across the border and drop it off on a siding there. The locomotives then return to the U.S. light. NdeM locomotives are allowed to pull rolling stock across the border onto a siding in Nogales, Arizona, and then return light to Mexico. I imagine that customs officials in both countries inspect the cargo before it is moved on toward its destination.