Mexican Federal Highway 40

From Reynosa, Tamaulipas, to La Junta, Nuevo León, the roadway is a 4-lane divided unrestricted access road. At La Junta the highway is separated into Fed. 40 and Fed. 40D. Fed. 40 continues as a 2-lane undivided road, passing through several small towns including:

• Peña Blanca, Nuevo León
• General Bravo, Nuevo León
• China, Nuevo León
• Cadereyta Jiménez, Nuevo León

From Monterrey, Nuevo León, to Saltillo, Coahuila, Fed. 40 is a 4-lane divided unrestricted access road. The highway crosses the northern end of the Sierra Madre Oriental that divides Coahuila and Nuevo León.

From Saltillo the road continues west as a 4-lane unrestricted access road. After the town of El Mesón, the road splits into the 4-lane toll Road Fed. 40D and a 2-lane undivided unrestricted Fed. 40. Both roads merge again in the town of 28 de Agosto and begin another section of 4-lane divided unrestricted highway. A few kilometers ahead is the road junction south to Parras de la Fuente. At La Cuchilla the road splits again into Fed. 40 and Fed. 40D. From there, one may take Fed. 30 to San Pedro, which eventually becomes a 4-lane divided unrestricted road and leads directly to northern Torreón. At the city of Matamoros, Fed. 40 and Fed. 40D merge again into a 4-lane divided unrestricted highway until one reaches Torreón.

This section is the east–west section across the central Mexican Plateau.

Torreon, Coahuila, and Gómez Palacio, Durango, form a metro area. At Gómez Palacio, Fed. 40 merges with Fed. 49 that comes from the north. At Gómez Palacio one can choose between Fed's 40 or 49 and Feds 40D or 49D; both roads are 4-lane divided until the first toll plaza.

At Gómez Palacio one can choose between the toll road and the unrestricted road. At Cuencamé, Durango, the roads splits: Fed. 49 continues south to Zacatecas and Mexico City, and Fed. 40 continues west to Durango.

This section of the highway crosses the Sierra Madre Occidental, and is narrow with many curves, particularly the portion known as the Espinazo del Diablo west of the Sierra crest. It has recently been bypassed by the new Fed. 40D. The old Fed. 40 can take up to 8 hours to travel, while Fed. 40D should only take 3 hours. During the winter months there is the added danger of ice. When going eastbound, Mazatlán to Durango, after reaching the top of the Sierra Madre Occidental, Fed. 40 becomes more linear, and it goes through the towns of La Ciudad, El Salto, and El Soldado. It continues linear up to a point around 30 kilometers from Durango, and it again goes downhill with many curves. In all the downhill sections, the use of engine brake is advised.

Improvement of the corridor between Durango and Mazatlán has shortened travel time between the two cities from approximately eight hours to slightly under two and one-half hours. In addition to being a boon to travel and commerce between Durango and Sinaloa and points beyond, authorities expected enhanced security in the region due to quicker access and mobility of the military. The new highway, known officially as Autopista Durango-Mazatlán, was finished in 2012, and inaugurated by President Enrique Peña Nieto on October 17, 2013.[7] The route passes through and over the Sierra Madre Occidental by way of 63 new tunnels totaling nearly 18 km (11 mi) in length, and 115 new bridges, eight of which are over 270 m (890 ft) high.[8] The most important of the latter is the Baluarte Bridge, spanning the Baluarte River which forms the border between the states of Durango and Sinaloa.[9] At 1,124 m (3,688 ft) in length, it is the world's longest cable-stayed bridge. With 403 m (1,322 ft) between the bridge deck and the river below, it is the third-highest cable-stayed bridge in the world, the seventh-highest bridge overall and the highest bridge in the Americas.