The Mexico Free zone encompasses areas along Mexico’s northern border. Yet, the entire Baja peninsula and a large portion of Sonora are included in the free zone. For all other Mexican border states, it is the area between 20 and 26 km (12 to 16 miles) from the border. The entire State of Quintana Roo is FREE as well but you need a TIP to drive there so be sure to get it at the border if you are going to the Cancun Area.
The Sonora designation is important, because it’s illegal to cross out of the Free Zone without a Temporary Vehicle Import Permit. The free zone in Sonora lies to the northwest of Mexico Federal Highway Number 2, starting at Agua Prieta. It extends through Cananea, to where it intersects with Mexican Federal Highway 15 in Imuris. From Imuris, all of the areas to the north and west of Mexico Federal Highway 15 are included. Kilometer 98, southeast of Empalme, is where the free zone ends.
Mexico makes it easier for those traveling outside the Free Zone in Sonora by offering the Sonora-only Temporary Importation Permit.