A breathtaking bird's-eye view freezes a lone intercity bus as it negotiates the dramatic horseshoe curve of the Cuesta de Mamulique — the rugged mountain grade on the Carretera Nacional linking Mexico City to Laredo, Texas — sometime in the early-to-mid 1940s. Photographer H.K. López captured the scene from high on the Sierra ridge, the sinuous road carving a pale ribbon through dense chaparral while the mountain ranges of Nuevo León stack in hazy layers toward the horizon. A low retaining wall hugs the outer edge of the curve, the only barrier between the bus and a long drop into the barranca below. The real-photo printing process renders every tire track and boulder with tactile clarity, making this a prized document of Mexico's ambitious mid-century highway program and the hardy coaches that ran it. The reverse is a clean, unused Tarjeta Postal blank with only a handwritten price notation "200" in pencil.