Dating to Spanish settlement in New Mexico and the Camino Real, the escarpment at La Bajada, which lies southwest of Santa Fe, posed a formidable challenge to the development of a transportation network along the Rio Grande Valley. In 1909 work started on the roadbed and cuts were made into the solid basalt caprock and retaining walls were built of dry masonry. The project was heralded as an engineering wonder along New Mexico’s Scenic Highway that soon became a part of the National Old Trails Road Ocean-to-Ocean Highway. In 1924 the road was realigned along the upper slopes of the escarpment. With the creation of the federal highway system in 1926, this improved roadway became a part of the U.S. 66 and U.S. 85 alignment. The alignment remained a part of the highway system until 1931 when a new alignment was completed along a gentler slope three miles to the south.