CORRECTION - CLARIFICATION.......
I received a PM about the Mexican trucks - I do not respond well to these kinds of PMs and generally block the sender - this is a forum and all comments should be addressed to the entire forum - that is what a forum is about....
Yes, Mexican trucks do enter the US at almost every border crossing. They then proceed to warehouses, terminals, distribution centers, customs houses, within a few miles of the border. A specific route within a specific time frame. Once there they either unload or swap trailers - and then return to Mexico.
These trucks are mostly pre-cleared and permitted a specific destination and route. They do not go further than a few miles into the US. We have seen trucks hauling chilis cross south of Deming and haul all the way to the chili cannery in Deming. Others cross all along the US - Mexico border all day everyday with hundreds of trucks crossing at each crossing everyday.
I could go back to find the stories about Mexican trucks finally being allowed into the US and what the requirements are but I am sure others on this forum who regularly follow the happenings will be well aware of all the facts - instead of the rumors that seem to abound from those who obviously have little to no real knowledge of these things yet insist on posting maligning and derogatory comments about an entire country and its people. Those who feel this way about Mexico and Mexicans probably should not visit as you will probably be very unhappy.
As far as Mexican trucks - Kenworth has had a huge manufacturing plant in Mexicali for decades turning out thousands of trucks for the Mexican truckers and trucking companies. . . . http://www.kenmex.com/index.html . . . they do not have to go to the US to purchase these trucks. If you look at the history you will find Kenworth has been building trucks in Mexico since 1959. Freightliner (Daimler) has been building trucks in Mexico since 1991 . . . http://www.daimler-trucksnorthamerica.com/inside/where-we-work-plants.aspx . . . a great many other US manufacturers including all three of the BIG 3 car companies in the US have huge plants building all kinds of vehicles for the US in MExico. Companies like Caterpillar and John Deere also have huge plants producing motorized equipment for the US market as well as the Mexican market. Lot of tires and all kinds of other automotive equipment is also produced in Mexico.
We do see trucks in the US with both US and Mexican license plates. These are US companies who are also licensed to operate in Mexico. All trucks operating in the US are subject of frequent and unexpected inspections in almost every state. Any suspect vehicle is inspected in almost every state and weigh stations. It may be remotely possible for a Mexican truck to get into the US and to travel more miles than they are supposed to but the odds are slim - there are just too many regulations and weigh stations checking - as well as spot checks. As a former long time trucker I personally know for a fact you cannot travel very far in the US in a commercial vehicle without having to at least clear a weigh station. I think maybe some people out there just like making things up.