Around the time we knocked down the statue of Hussein in Iraq. I think it was about 2003 or so as the Trane AC man was putting in a new unit when that statue fell that the truck traffic here doubled due to NAFTA. It was trucks hauling goods from Mexico not Mexican drivers. I do recall Tennessee was giving Drivers licenses to illegals. The truck traffic went up with NAFTA as many appliances and other items were made in Mexico. It was approximately then.
I pulled up the NAFTA document/report that states the other countries are to have their roads open to the others vehicles/trucks by 2000.
http://www.citizen.org/Page.aspx?pid=5251