49) is a free (libre) part of the federal highways corridors () of Mexico.

[6] The highway runs northwest-southeast in the western regions of the Mexican Plateau.

49 has two separate improved segments: The first segment runs from Ciudad Jiménez, Chihuahua to just northwest of Fresnillo, Zacatecas.

40 for 104.6 km (65 mi) from Gómez Palacio to Cuencamé.

[7] The second segment runs from Las Arcinas, Zacatecas to San Luis Potosí, San Luis Potosí.