Chihuahua al Pacífico Railroad

Interesting: https://planeta.com/chihuahua-al-pacifico/

For visitors to the Copper Canyon, a train ride is a must. The famous train runs from Chihuahua City to Los Mochis, Sinaloa on the Pacific coast.

Known as ChP or Chepe, the dramatic 653-kilometer (406-mile) trip takes 16 hours, including brief stops on the first-class run and longer and more frequent stops on the second-class service. The train roars through the Sierra Madre Occidental, generally barreling through the mountainsides, although there are plenty of switchbacks. This railroad line boasts 87 tunnels and 37 soaring bridges, making it a world-class train trip.
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I rode the CHP on a 1990s American Orient Express trip Chihuahua - Los Mochis - Nogales. There are many spectacular views, quite a few loops and tunnels but no actual switchbacks. Much of the grade is well up on the side of the canyons. In places the slope below the tracks was decorated with unsalvageable covered hoppers etc. from old wrecks. There is a local population in the area, whose road access is terrible to nonexistent. This is why the 2nd class service was kept on the line when Mexico abandoned almost all of its passenger trains.

Google maps does show the CHP railroad if you zoom in far enough. The endpoints of the canyon ride are roughly Creel on the east, the big reservoir at the Chichuahua/Sinaloa boundary on the west.