High above the Sierra Madre, a lone automobile rounds the dramatic Curva de Mamulique — a breathtaking hairpin carved into pale limestone cliffs along the Carretera México–Laredo, captured in a crisp real-photo postcard from the early 1930s. Marked kilometer 230 on the highway, this pass near Monterrey, Nuevo León, was one of the most photographed and feared stretches of the nascent Pan-American road, where sheer cliff faces dropped away to reveal vast mountain panoramas stretching into haze. The narrow two-lane road with its modest whitewashed markers speaks to the audacity of early motoring tourists who made the Laredo-to-Mexico City run — the same route used by travelers whose correspondence appears elsewhere in this collection. A hand-drawn arrow and notation "230" are inscribed directly on the image, suggesting this may be from a numbered documentary series cataloguing the highway's landmarks for tourism or engineering purposes.