Saltillo-San Luis Potosi-Guadalajara-San Miguel de Allende-Arco Norte
Map to get almost anywhere in Colonial Mexico. From San Roberto Jct. to Real de Catorce, to San Luis Potosi - San Miguel de Allende - Guanajuato, Queretaro - Arco Norte - Toluca - Morelia. Aguascalientes.
Most popular route. Toll roads are good and it is a straight shot from Nuevo Laredo to central or colonial Mexico and the Pacific Coast towns like Puerto Vallarta and Mazatlan.
Concerned about safety? Want to completely avoid Tamaulipas and much of Veracruz?